Take an optional rabbit user name as input

Newer versions of rabbitmq (3.3 and later) do not allow the 'guest'
user to access on non-local interfaces.

- Added a new config RABBIT_USERID which defaults to stackrabbit
- Invoked config scripts using that variable

Adopted from:
https://review.openstack.org/#/c/107779/

Change-Id: I43a231c9611b4cc2e390b603aa3bfb49c915bdc5
Closes-Bug: #1343354
Co-Authored-By: Scott Moser <smoser@ubuntu.com>
diff --git a/lib/nova b/lib/nova
index 4c86d79..cbfbdfa 100644
--- a/lib/nova
+++ b/lib/nova
@@ -587,8 +587,8 @@
         fi
 
         $NOVA_BIN_DIR/nova-manage --config-file $NOVA_CELLS_CONF db sync
-        $NOVA_BIN_DIR/nova-manage --config-file $NOVA_CELLS_CONF cell create --name=region --cell_type=parent --username=guest --hostname=$RABBIT_HOST --port=5672 --password=$RABBIT_PASSWORD --virtual_host=/ --woffset=0 --wscale=1
-        $NOVA_BIN_DIR/nova-manage cell create --name=child --cell_type=child --username=guest --hostname=$RABBIT_HOST --port=5672 --password=$RABBIT_PASSWORD --virtual_host=child_cell --woffset=0 --wscale=1
+        $NOVA_BIN_DIR/nova-manage --config-file $NOVA_CELLS_CONF cell create --name=region --cell_type=parent --username=$RABBIT_USERID --hostname=$RABBIT_HOST --port=5672 --password=$RABBIT_PASSWORD --virtual_host=/ --woffset=0 --wscale=1
+        $NOVA_BIN_DIR/nova-manage cell create --name=child --cell_type=child --username=$RABBIT_USERID --hostname=$RABBIT_HOST --port=5672 --password=$RABBIT_PASSWORD --virtual_host=child_cell --woffset=0 --wscale=1
     fi
 }