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
It prints more than just the MYSQL_ROOT_PASSWORD env variable, doesn't it?

We don't necessarily have to show all of them, but maybe something like:
ENV_VAR_1=value
ENV_VAR_2=value
....(output trunated)
ENV_VAR_3=value

Where env var 1-3 are the interesting ones that we setup.