Add database pod and service for ruby sample app demo

- [x] update ruby-sample-app image with MySQL connection for Sinatra app 
- [x] change docker image URL with OpenShift official image for ruby-sample-app - https://github.com/openshift/ruby-hello-world/pull/5
If you want to serialize the file with a JSON library, it will fail because it's an empty string. I just update the JSON files to be valid in case someone would use them.