Python - DocumentRoot logic, Repository Layout simplification

https://trello.com/c/XdJdVHU9 - origin_cartridge_138

- new Repository Layout:

    wsgi.py             WSGI entry-point
    setup.py            Standard setup.py
    .openshift/         OpenShift specific files
        action_hooks/   Action Hooks
        markers/        Marker files

- backward compatible control script logic to select DocumentRoot
- move mod_wsgi.so LoadModule into separate wsgi.conf config files
- add $OPENSHIFT_PYTHON_WSGI_APPLICATION ENV VAR to set
  alternative WSGI entry-point
- cucumber tests for WSGI entry-point
- add cartridge_guide documentation
- various cleanup in control scripts