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

[test] [extended:cartridge]