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
diff --git a/lib/rpc_backend b/lib/rpc_backend
index 27d3ba3..6b334a9 100644
--- a/lib/rpc_backend
+++ b/lib/rpc_backend
@@ -138,6 +138,13 @@
         fi
         # change the rabbit password since the default is "guest"
         sudo rabbitmqctl change_password guest $RABBIT_PASSWORD
+        if is_service_enabled n-cell; then
+            # Add partitioned access for the child cell
+            if [ -z `sudo rabbitmqctl list_vhosts | grep child_cell` ]; then
+                sudo rabbitmqctl add_vhost child_cell
+                sudo rabbitmqctl set_permissions -p child_cell guest ".*" ".*" ".*"
+            fi
+        fi
     elif is_service_enabled qpid; then
         echo_summary "Starting qpid"
         restart_service qpidd