updating bookbinder release to address nokogiri security warning
diff --git a/book/Gemfile.lock b/book/Gemfile.lock
index 3c483c0..7bcd1e6 100644
--- a/book/Gemfile.lock
+++ b/book/Gemfile.lock
@@ -1,43 +1,40 @@
 GEM
   remote: https://rubygems.org/
   specs:
-    activesupport (4.2.7.1)
+    activesupport (4.2.10)
       i18n (~> 0.7)
-      json (~> 1.7, >= 1.7.7)
       minitest (~> 5.1)
       thread_safe (~> 0.3, >= 0.3.4)
       tzinfo (~> 1.1)
-    addressable (2.4.0)
+    addressable (2.5.2)
+      public_suffix (>= 2.0.2, < 4.0)
     ansi (1.5.0)
-    bookbindery (9.12.0)
+    backports (3.11.1)
+    bookbindery (10.1.12)
       ansi (~> 1.4)
       css_parser
       elasticsearch
       fog-aws (~> 0.7.1)
       font-awesome-sass
       git (~> 1.2.8)
-      middleman (~> 3.4.0)
-      middleman-livereload (~> 3.4.3)
-      middleman-syntax (~> 2.0)
-      nokogiri (= 1.6.7.2)
+      middleman (= 4.1.10)
+      middleman-compass
+      middleman-livereload
+      middleman-sprockets
+      middleman-syntax (= 2.1.0)
+      nokogiri (= 1.8.1)
       puma
       rack-rewrite
       redcarpet (~> 3.2.3)
       rouge (!= 1.9.1)
       therubyracer
-      thor
-    builder (3.2.2)
-    capybara (2.4.4)
-      mime-types (>= 1.16)
-      nokogiri (>= 1.3.3)
-      rack (>= 1.0.0)
-      rack-test (>= 0.5.4)
-      xpath (~> 2.0)
-    chunky_png (1.3.6)
+      thor (= 0.19.1)
+    builder (3.2.3)
+    chunky_png (1.3.10)
     coffee-script (2.4.1)
       coffee-script-source
       execjs
-    coffee-script-source (1.10.0)
+    coffee-script-source (1.12.2)
     compass (1.0.3)
       chunky_png (~> 1.2)
       compass-core (~> 1.0.2)
@@ -50,147 +47,152 @@
       sass (>= 3.3.0, < 3.5)
     compass-import-once (1.0.5)
       sass (>= 3.2, < 3.5)
-    css_parser (1.4.5)
+    concurrent-ruby (1.0.5)
+    contracts (0.13.0)
+    css_parser (1.6.0)
       addressable
-    elasticsearch (2.0.0)
-      elasticsearch-api (= 2.0.0)
-      elasticsearch-transport (= 2.0.0)
-    elasticsearch-api (2.0.0)
+    dotenv (2.2.1)
+    elasticsearch (6.0.1)
+      elasticsearch-api (= 6.0.1)
+      elasticsearch-transport (= 6.0.1)
+    elasticsearch-api (6.0.1)
       multi_json
-    elasticsearch-transport (2.0.0)
+    elasticsearch-transport (6.0.1)
       faraday
       multi_json
     em-websocket (0.5.1)
       eventmachine (>= 0.12.9)
       http_parser.rb (~> 0.6.0)
     erubis (2.7.0)
-    eventmachine (1.2.0.1)
-    excon (0.51.0)
+    eventmachine (1.2.5)
+    excon (0.60.0)
     execjs (2.7.0)
-    faraday (0.9.2)
+    faraday (0.14.0)
       multipart-post (>= 1.2, < 3)
-    ffi (1.9.14)
+    fast_blank (1.0.0)
+    fastimage (2.1.1)
+    ffi (1.9.21)
     fog-aws (0.7.6)
       fog-core (~> 1.27)
       fog-json (~> 1.0)
       fog-xml (~> 0.1)
       ipaddress (~> 0.8)
-    fog-core (1.42.0)
+    fog-core (1.45.0)
       builder
-      excon (~> 0.49)
+      excon (~> 0.58)
       formatador (~> 0.2)
     fog-json (1.0.2)
       fog-core (~> 1.0)
       multi_json (~> 1.10)
-    fog-xml (0.1.2)
+    fog-xml (0.1.3)
       fog-core
-      nokogiri (~> 1.5, >= 1.5.11)
-    font-awesome-sass (4.6.2)
+      nokogiri (>= 1.5.11, < 2.0.0)
+    font-awesome-sass (4.7.0)
       sass (>= 3.2)
     formatador (0.2.5)
     git (1.2.9.1)
-    haml (4.0.7)
+    haml (5.0.4)
+      temple (>= 0.8.0)
       tilt
-    hike (1.2.3)
-    hooks (0.4.1)
-      uber (~> 0.0.14)
+    hamster (3.0.0)
+      concurrent-ruby (~> 1.0)
+    hashie (3.5.7)
     http_parser.rb (0.6.0)
     i18n (0.7.0)
     ipaddress (0.8.3)
-    json (1.8.3)
-    kramdown (1.12.0)
+    kramdown (1.16.2)
     libv8 (3.16.14.7)
     listen (3.0.8)
       rb-fsevent (~> 0.9, >= 0.9.4)
       rb-inotify (~> 0.9, >= 0.9.7)
-    middleman (3.4.1)
+    memoist (0.16.0)
+    middleman (4.1.10)
       coffee-script (~> 2.2)
-      compass (>= 1.0.0, < 2.0.0)
       compass-import-once (= 1.0.5)
-      execjs (~> 2.0)
       haml (>= 4.0.5)
       kramdown (~> 1.2)
-      middleman-core (= 3.4.1)
-      middleman-sprockets (>= 3.1.2)
+      middleman-cli (= 4.1.10)
+      middleman-core (= 4.1.10)
       sass (>= 3.4.0, < 4.0)
-      uglifier (~> 2.5)
-    middleman-core (3.4.1)
-      activesupport (~> 4.1)
+    middleman-cli (4.1.10)
+      thor (>= 0.17.0, < 2.0)
+    middleman-compass (4.0.1)
+      compass (>= 1.0.0, < 2.0.0)
+      middleman-core (>= 4.0.0)
+    middleman-core (4.1.10)
+      activesupport (~> 4.2)
+      addressable (~> 2.3)
+      backports (~> 3.6)
       bundler (~> 1.1)
-      capybara (~> 2.4.4)
+      contracts (~> 0.13.0)
+      dotenv
       erubis
-      hooks (~> 0.3)
+      execjs (~> 2.0)
+      fast_blank
+      fastimage (~> 2.0)
+      hamster (~> 3.0)
+      hashie (~> 3.4)
       i18n (~> 0.7.0)
-      listen (~> 3.0.3)
-      padrino-helpers (~> 0.12.3)
+      listen (~> 3.0.0)
+      memoist (~> 0.14)
+      padrino-helpers (~> 0.13.0)
+      parallel
       rack (>= 1.4.5, < 2.0)
-      thor (>= 0.15.2, < 2.0)
-      tilt (~> 1.4.1, < 2.0)
+      sass (>= 3.4)
+      servolux
+      tilt (~> 1.4.1)
+      uglifier (~> 3.0)
     middleman-livereload (3.4.6)
       em-websocket (~> 0.5.1)
       middleman-core (>= 3.3)
       rack-livereload (~> 0.3.15)
-    middleman-sprockets (3.4.2)
-      middleman-core (>= 3.3)
-      sprockets (~> 2.12.1)
-      sprockets-helpers (~> 1.1.0)
-      sprockets-sass (~> 1.3.0)
+    middleman-sprockets (4.1.1)
+      middleman-core (~> 4.0)
+      sprockets (>= 3.0)
     middleman-syntax (2.1.0)
       middleman-core (>= 3.2)
       rouge (~> 1.0)
-    mime-types (3.1)
-      mime-types-data (~> 3.2015)
-    mime-types-data (3.2016.0521)
-    mini_portile2 (2.0.0)
-    minitest (5.9.0)
-    multi_json (1.12.1)
+    mini_portile2 (2.3.0)
+    minitest (5.11.3)
+    multi_json (1.13.1)
     multipart-post (2.0.0)
-    nokogiri (1.6.7.2)
-      mini_portile2 (~> 2.0.0.rc2)
-    padrino-helpers (0.12.8)
+    nokogiri (1.8.1)
+      mini_portile2 (~> 2.3.0)
+    padrino-helpers (0.13.3.4)
       i18n (~> 0.6, >= 0.6.7)
-      padrino-support (= 0.12.8)
-      tilt (~> 1.4.1)
-    padrino-support (0.12.8)
+      padrino-support (= 0.13.3.4)
+      tilt (>= 1.4.1, < 3)
+    padrino-support (0.13.3.4)
       activesupport (>= 3.1)
-    puma (3.6.0)
-    rack (1.6.4)
+    parallel (1.12.1)
+    public_suffix (3.0.1)
+    puma (3.11.2)
+    rack (1.6.8)
     rack-livereload (0.3.16)
       rack
     rack-rewrite (1.5.1)
-    rack-test (0.6.3)
-      rack (>= 1.0)
-    rb-fsevent (0.9.7)
-    rb-inotify (0.9.7)
-      ffi (>= 0.5.0)
+    rb-fsevent (0.10.2)
+    rb-inotify (0.9.10)
+      ffi (>= 0.5.0, < 2)
     redcarpet (3.2.3)
     ref (2.0.0)
     rouge (1.11.1)
-    sass (3.4.22)
-    sprockets (2.12.4)
-      hike (~> 1.2)
-      multi_json (~> 1.0)
-      rack (~> 1.0)
-      tilt (~> 1.1, != 1.3.0)
-    sprockets-helpers (1.1.0)
-      sprockets (~> 2.0)
-    sprockets-sass (1.3.1)
-      sprockets (~> 2.0)
-      tilt (~> 1.1)
+    sass (3.4.25)
+    servolux (0.13.0)
+    sprockets (3.7.1)
+      concurrent-ruby (~> 1.0)
+      rack (> 1, < 3)
+    temple (0.8.0)
     therubyracer (0.12.2)
       libv8 (~> 3.16.14.0)
       ref
     thor (0.19.1)
-    thread_safe (0.3.5)
+    thread_safe (0.3.6)
     tilt (1.4.1)
-    tzinfo (1.2.2)
+    tzinfo (1.2.5)
       thread_safe (~> 0.1)
-    uber (0.0.15)
-    uglifier (2.7.2)
-      execjs (>= 0.3.0)
-      json (>= 1.8.0)
-    xpath (2.0.0)
-      nokogiri (~> 1.3)
+    uglifier (3.2.0)
+      execjs (>= 0.3.0, < 3)
 
 PLATFORMS
   ruby
@@ -200,4 +202,4 @@
   libv8 (= 3.16.14.7)
 
 BUNDLED WITH
-   1.11.2
+   1.16.0