Add newrelic mysql plugin support to stack_commons::newrelic

I've just followed their logic : https://github.com/newrelic-platform/newrelic_plugins_chef/blob/master/definitions/verify_java.rb
I would say ohai should populate this whatever the java source. https://github.com/opscode/ohai/blob/master/lib/ohai/plugins/java.rb#L29
I'm really looking forward to refactor this recipe :wink:.