Website: update Gemfile dependencies

Updating Gemfile dependencies to try fix Travis (see https://github.com/apache/bookkeeper/issues/2252)

Also fixing https://www.cvedetails.com/cve/CVE-2018-17567/ in the meantime

You can find the staging website  https://aluccaroni.github.io/bookkeeper-staging-site

Reviewers: Enrico Olivelli <eolivelli@gmail.com>, Sijie Guo <None>

This closes #2256 from aluccaroni/master
diff --git a/site/Gemfile b/site/Gemfile
index cc4f51e..16ae2ae 100644
--- a/site/Gemfile
+++ b/site/Gemfile
@@ -1,7 +1,7 @@
 source 'https://rubygems.org'
 
-ruby '>=2.3.1'
+ruby '>=2.4.0'
 
-gem 'jekyll', '3.7.0'
-gem 'nokogiri', '1.8.2'
-gem 'jekyll-toc', '0.2.1'
+gem 'jekyll', '3.8.6'
+gem 'nokogiri', '1.10.7'
+gem 'jekyll-toc', '0.12.2'
diff --git a/site/Gemfile.lock b/site/Gemfile.lock
index 9854897..1daa761 100644
--- a/site/Gemfile.lock
+++ b/site/Gemfile.lock
@@ -1,20 +1,20 @@
 GEM
   remote: https://rubygems.org/
   specs:
-    addressable (2.5.2)
-      public_suffix (>= 2.0.2, < 4.0)
+    addressable (2.7.0)
+      public_suffix (>= 2.0.2, < 5.0)
     colorator (1.1.0)
-    concurrent-ruby (1.0.5)
+    concurrent-ruby (1.1.5)
     em-websocket (0.5.1)
       eventmachine (>= 0.12.9)
       http_parser.rb (~> 0.6.0)
-    eventmachine (1.2.5)
-    ffi (1.9.18)
+    eventmachine (1.2.7)
+    ffi (1.12.1)
     forwardable-extended (2.6.0)
     http_parser.rb (0.6.0)
-    i18n (0.9.3)
+    i18n (0.9.5)
       concurrent-ruby (~> 1.0)
-    jekyll (3.7.0)
+    jekyll (3.8.6)
       addressable (~> 2.4)
       colorator (~> 1.0)
       em-websocket (~> 0.5)
@@ -27,32 +27,30 @@
       pathutil (~> 0.9)
       rouge (>= 1.7, < 4)
       safe_yaml (~> 1.0)
-    jekyll-sass-converter (1.5.1)
+    jekyll-sass-converter (1.5.2)
       sass (~> 3.4)
-    jekyll-toc (0.2.1)
-      nokogiri (~> 1.6)
-    jekyll-watch (2.0.0)
+    jekyll-toc (0.12.2)
+      nokogiri (~> 1.9)
+    jekyll-watch (2.2.1)
       listen (~> 3.0)
-    kramdown (1.16.2)
-    liquid (4.0.0)
-    listen (3.1.5)
-      rb-fsevent (~> 0.9, >= 0.9.4)
-      rb-inotify (~> 0.9, >= 0.9.7)
-      ruby_dep (~> 1.2)
+    kramdown (1.17.0)
+    liquid (4.0.3)
+    listen (3.2.1)
+      rb-fsevent (~> 0.10, >= 0.10.3)
+      rb-inotify (~> 0.9, >= 0.9.10)
     mercenary (0.3.6)
-    mini_portile2 (2.3.0)
-    nokogiri (1.8.2)
-      mini_portile2 (~> 2.3.0)
-    pathutil (0.16.1)
+    mini_portile2 (2.4.0)
+    nokogiri (1.10.7)
+      mini_portile2 (~> 2.4.0)
+    pathutil (0.16.2)
       forwardable-extended (~> 2.6)
-    public_suffix (3.0.1)
-    rb-fsevent (0.10.2)
-    rb-inotify (0.9.10)
-      ffi (>= 0.5.0, < 2)
-    rouge (3.1.1)
-    ruby_dep (1.5.0)
-    safe_yaml (1.0.4)
-    sass (3.5.5)
+    public_suffix (4.0.3)
+    rb-fsevent (0.10.3)
+    rb-inotify (0.10.1)
+      ffi (~> 1.0)
+    rouge (3.15.0)
+    safe_yaml (1.0.5)
+    sass (3.7.4)
       sass-listen (~> 4.0.0)
     sass-listen (4.0.0)
       rb-fsevent (~> 0.9, >= 0.9.4)
@@ -62,12 +60,12 @@
   ruby
 
 DEPENDENCIES
-  jekyll (= 3.7.0)
-  jekyll-toc (= 0.2.1)
-  nokogiri (= 1.8.2)
+  jekyll (= 3.8.6)
+  jekyll-toc (= 0.12.2)
+  nokogiri (= 1.10.7)
 
 RUBY VERSION
-   ruby 2.4.1p111
+   ruby 2.4.0p0
 
 BUNDLED WITH
-   1.16.2
+   2.1.4
diff --git a/site/Makefile b/site/Makefile
index 5c20bb6..37af9b9 100644
--- a/site/Makefile
+++ b/site/Makefile
@@ -21,6 +21,7 @@
 		--config _config.yml
 
 apache: clean
+	gem install bundler
 	JEKYLL_ENV=production $(JEKYLL) build \
 		--config _config.yml,_config.apache.yml