[WIP] Add database pod and service for ruby sample app demo

- [ ] update ruby-sample-app image with MySQL connection for Sinatra app https://github.com/openshift/ruby-hello-world/pull/5
- [ ] change docker image URL with OpenShift official image for ruby-sample-app
Please check the second task in the PR description and the PR I opened. Of course, but now is WIP and I'm using my own repo.