Basic cells support

Adds support for running a region and child cell within a single
devstack environment.

README.md has been updated with some info on getting started.

Rebased/updated from initial work by Andrew Laski <andrew.laski@rackspace.com>.

Change-Id: Ic181da2180ccaa51df7efc9d66f7ccb820aac19b
Merge remote-tracking branch 'm_src_repo/citrix-fixes' into build-temp