* Partial revert of 0a82af18ab
to restore main() method
* Add global `application` variable which will be set by main method to
problem to preserve the fix from 0a82af18ab.
* Add check for application name starting with '_mod_wsgi' to ensure
application runs in Devstack as well (Devstack does not use the entry point)
* Modify Devstack plugin to run WSGI entry point rather than app/wsgi.py from
module directory.
Change-Id: I07001dccb663ed4e6e3347089ab96e6f8ec196d4
Story: 2001197
Task: 5702
257fb55635