Prevent project_id overwriting from OSAPI request parameters.
The patch is actually very simple (nova/api/openstack/wsgi.py) but
needs significant test adjustments (nova/tests/*) to pass.
Fixes bug 904072. Patch from Vish Ishaya and Mark McLoughlin.
Change-Id: I66ea0f178ce6271ec1020e9f1a73bd4e8c83ddab