Opt-out of service catalog

Introducing a config option 'include_service_catalog' to indicate whether
service catalog is needed. If the 'include_service_catalog' option is set to
False, middleware will not ask for service catalog on token validation and will
not set the X-Service-Catalog header.

This option is backward compatible as it is default to True.

DocImpact
Fixed bug 1228317

Change-Id: Id8c410a7ae0443ac425d20cb9c6a24ee5bb2cb8d
Merge "Opt-out of service catalog"