Full Glance functionality requires Glance being run in a configuration
where it can spawn long-running task threads. The default uwsgi mode
does not allow this, and the current workaround is to set WSGI_MODE
to something other than uwsgi to get the devstack code to deploy
Glance as a standalone service. Since this affects the entire rest of
the deployment, this patch separates out a flag to control this behavior
specifically for Glance. When WSGI_MODE=uwsgi, control of the Glance
deployment mechanism is allowed via GLANCE_STANDALONE=True|False. If
WSGI_MODE!= uwsgi then we deploy standalone Glance anyway.
Change-Id: I79068ce0bd7414bc48ff534ee22f0de5d7b091cb
09eea0b20b