Change Ruby interpreter version

Currently the Gemfile specifies ruby_19 for MRI gems and jruby
for jruby ones.

Until now this has not caused any trouble. However now ruby 2.0.0
is released this is no longer kosher.

Since we are not supporting ruby 1.8.7 we will change the ruby_19
setting to just ruby

Gemfile

@@ -19,9 +19,9 @@ gem 'jquery-rails'
 gem 'logstash-event', '~>1.1.5'
 
 group :development, :test do
-  gem 'simplecov', :require => false, :platform => :ruby_19
+  gem 'simplecov', :require => false, :platform => :ruby
   gem 'capybara', '>=1.1.2'
-  gem 'sqlite3', :platform => :ruby_19
+  gem 'sqlite3', :platform => :ruby
 
   gem 'jdbc-sqlite3', :platform => :jruby
   gem 'activerecord-jdbcsqlite3-adapter', :platform => :jruby