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
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```
{
      "name": "MYSQL_DATABASE",
      "description": "database name",
      "value": "default"
}
```
?