Hierarchical Multitenacy

This change will create the concept of hierarchical projects at Keystone.
Implements: Blueprint hierarchical-multitenancy

Change-Id: If6e91583d2a4ffbf821f484e464927aeac240281
Merge branch 'hierarchical_projects' of https://github.com/andre-lsd/keystone into hierarchical_projects

Conflicts:
	keystone/assignment/backends/sql.py
	keystone/assignment/controllers.py
	keystone/assignment/core.py
	keystone/token/providers/common.py