Use uwsgi for glance-api

This commit adds support for deploying glance as a wsgi script under
uwsgi. To get around limitations in the uwsgi protocol when using
python3 for chunked encoding we have to setup uwsgi in http mode on a
random port listening on localhost and use mod_proxy to forward the
incoming requests. The alternative approach of having apache buffer the
requests locally with the send_cl option with mod_proxy_uwsgi only
worked on python2 and also has the limitation that apache is buffering
the entire chunked object, which could be several gigabytes in size.

Depends-On: I089a22a4be4227a551c32442dba27c426f54c87d
Change-Id: Ie98fb7da5e8ecfa49cd680b88139cb7034d5f88f
4 files changed