Adds NoAuthMiddleware for V3

Adds a V3 version of NoAuthMiddleware which returns a url which
unlike the V2 version does not include the tenant_id in the url.

Also fixes bug with the V2 version where it would create broken
urls on Windows because os.path.join was used

Partially implements blueprint v3-api-remove-project-id

DocImpact

Change-Id: I7ecffea52c3662344ac694997bb08a16506abbbd
Merge "Adds NoAuthMiddleware for V3"