API endpoints deployment via WSGI

[Eric K]

1. Provide WSGI application script file(s) (e.g. to be used by web server). There shouldn’t be any web server restriction and the application could be deploying to any web server that support WSGI applications.
2. Switch devstack jobs to deploy control-plane API services in WSGI with Apache. Usage of Apache is already the default in Devstack, let’s keep using it for consistency unless there is some efforts to support another web server but this is not the case at this time.

Openstack patches related to this effort can be found here: https://review.openstack.org/#/q/topic:goal-deploy-api-in-wsgi
More information on the community goal: https://governance.openstack.org/tc/goals/pike/deploy-api-in-wsgi.html