Add unit test for creating RequestContext
Add unit test for creating RequestContext

There wasn't a unit test that shows that AuthContextMiddleware
creates an oslo_context.RequestContext.

Change-Id: I9094df5c99121640668c8b468aa261d065b41d30
Partial-Bug: 1500222

openstack/keystone,dims/keystone,ilay09/keystone,himanshu-setia/keystone,himanshu-setia/keystone,ajayaa/keystone,mahak/keystone,klmitch/keystone,rajalokan/keystone,klmitch/keystone,ilay09/keystone,openstack/keystone,cernops/keystone,ilay09/keystone,mahak/keystone,maestro-hybrid-cloud/keystone,maestro-hybrid-cloud/keystone,ajayaa/keystone,openstack/keystone,mahak/keystone,cernops/keystone,rajalokan/keystone,rajalokan/keystone,dims/keystone