Bump and release 0.12.0

Align SDK major and minor version with PredictionIO
diff --git a/README.md b/README.md
index 3c94281..3ab8553 100644
--- a/README.md
+++ b/README.md
@@ -49,7 +49,7 @@
 Or using [Bundler](http://bundler.io/) with:
 
 ```
-gem 'predictionio', '0.9.6'
+gem 'predictionio', '0.12.0'
 ```
 
 ## Sending Events to Event Server
diff --git a/lib/predictionio/version.rb b/lib/predictionio/version.rb
index 61667cb..22c257d 100644
--- a/lib/predictionio/version.rb
+++ b/lib/predictionio/version.rb
@@ -14,5 +14,5 @@
 # limitations under the License.
 
 module PredictionIO
-  VERSION = '0.9.7'
+  VERSION = '0.12.0'
 end