Merge mysql wordpress deployment files

[cloud-pharaoh]

Deployment files:

• https://github.com/GoogleCloudPlatform/kubernetes-engine-samples/blob/master/cloudsql/mysql_wordpress_deployment.yaml
• https://github.com/GoogleCloudPlatform/kubernetes-engine-samples/blob/master/wordpress-persistent-disks/wordpress_cloudsql.yaml.template

The above 2 files are almost identical except for the fact that the latter is linked to this tutorial and uses persistent disks.
Some consideration needs to happen to assess how to best merge these or keep only one of them somehow to avoid this duplication.

[kurtisvg]

Please see #96 for more context.