Add clean.sh

clean.sh gets rid of all residue of running DevStack except installed
packages and pip modules.

And it eradicates rabbitmq-server and ts erlang dependencies as well as
the other RPC backends and databases.

Change-Id: I2b9a251a0a151c012bae85a5a2f9c2f72e7700be
diff --git a/lib/nova b/lib/nova
index 906a635..23346b7 100644
--- a/lib/nova
+++ b/lib/nova
@@ -106,6 +106,8 @@
         # Clean out the instances directory.
         sudo rm -rf $NOVA_INSTANCES_PATH/*
     fi
+
+    sudo rm -rf $NOVA_STATE_PATH $NOVA_AUTH_CACHE_DIR
 }
 
 # configure_novaclient() - Set config files, create data dirs, etc
@@ -308,9 +310,6 @@
                 sudo chown -R $STACK_USER $NOVA_INSTANCES_PATH
             fi
         fi
-
-        # Clean up old instances
-        cleanup_nova
     fi
 }