Remove Wordpress sources and replace them with download during build

With this PR merged, this repo will get rid of the wordpress sources in 'php' directory. Instead, the Wordpress will be installed during the `build`.

Users can change the version they want to install by altering the `install_version` variable in the `.openshift/hooks/build` script (TBD: make it configurable viac rhc env?).

I also added a quick patch for the 'setup' script which will prefill the input boxes with OpenShift environment values, which makes it easier for new users to pass (users now just hit 'Continue' button 3x ;-)