Merge pull request #4611 from murgatroid99/ruby_0.12_version_update

Update Ruby library version for next release

src/ruby/lib/grpc/version.rb

-# Copyright 2015, Google Inc.
+# Copyright 2015-2016, Google Inc.
 # All rights reserved.
 #
 # Redistribution and use in source and binary forms, with or without
@@ -29,5 +29,5 @@
 
 # GRPC contains the General RPC module.
 module GRPC
-  VERSION = '0.11.1'
+  VERSION = '0.12.0'
 end