Delete leaf project

Added is_leaf_project() method to assignments Core and
checking at delete_project from assignments Manager.
Merge branch 'hierarchical-projects-base' of https://github.com/rodrigods/keystone into delete-leaf-project

Conflicts:
	keystone/assignment/backends/kvs.py
Merge branch 'hierarchical-projects-base' of https://github.com/rodrigods/keystone into delete-leaf-project
Change is_leaf_project()

Change how the projects are listed
Merge branch 'hierarchical-projects-base' of https://github.com/rodrigods/keystone into delete-leaf-project
Merge branch 'hierarchical-projects-base' of https://github.com/rodrigods/keystone into delete-leaf-project
Adding tests for delete hierarchical project functionality.
Merge branch 'master' of https://github.com/openstack/keystone into delete-leaf-project
Merge branch 'delete-leaf-project' of https://github.com/rodrigods/keystone into delete-leaf-project
Deny not leaf parent_project update

This patch adds the feature to deny update a
project_parent_id if it isn't a leaf project in
the hierarchy.

Here is the expected behavior:
- Update a not leaf project should raise a ForbiddenAction
  error
- Update the parent_project_id to a not-existent project
  should raise a ProjectNotFound error

Tests were also added
Deny not leaf parent_project update

This patch adds the feature to deny update a
project_parent_id if it isn't a leaf project in
the hierarchy.

Here is the expected behavior:
- Update a not leaf project should raise a ForbiddenAction
  error
- Update the parent_project_id to a not-existent project
  should raise a ProjectNotFound error

Tests were also added
Merge branch 'leaf-projects-crud' of https://github.com/rodrigods/keystone into leaf-projects-crud
Merge branch 'hierarchical-projects-base' of https://github.com/rodrigods/keystone into leaf-projects-crud
Merge branch 'master' of https://github.com/openstack/keystone into leaf-projects-crud
Merge branch 'hierarchical-projects-base' of https://github.com/rodrigods/keystone into leaf-projects-crud
Merge branch 'hierarchical-projects-base' of https://github.com/rodrigods/keystone into leaf-projects-crud
Merge branch 'hierarchical-projects-base' of https://github.com/rodrigods/keystone into leaf-projects-crud
Merge pull request #1 from rodrigods/leaf-projects-crud

Leaf projects crud