Add delegated auth via oauth to keystone

Provide the ability for identity users to delegate roles to third party
consumers via the OAuth 1.0a specification. This functionality is being
provided as an extension.

blueprint: delegated-auth-via-oauth

SecurityImpact

Change-Id: Ic9b6c6f0643e4b83795b2d0426e3570cd83b55c4
Merge "Add delegated auth via oauth to keystone"