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/rpc_backend b/lib/rpc_backend
index 02614ea..bbd51f0 100644
--- a/lib/rpc_backend
+++ b/lib/rpc_backend
@@ -43,6 +43,38 @@
     fi
 }
 
+# clean up after rpc backend - eradicate all traces so changing backends
+# produces a clean switch
+function cleanup_rpc_backend {
+    if is_service_enabled rabbit; then
+        # Obliterate rabbitmq-server
+        uninstall_package rabbitmq-server
+        sudo killall epmd
+        if is_ubuntu; then
+            # And the Erlang runtime too
+            sudo aptitude purge -y ~nerlang
+        fi
+    elif is_service_enabled qpid; then
+        if is_fedora; then
+            uninstall_package qpid-cpp-server-daemon
+        elif is_ubuntu; then
+            uninstall_package qpidd
+        else
+            exit_distro_not_supported "qpid installation"
+        fi
+    elif is_service_enabled zeromq; then
+        if is_fedora; then
+            uninstall_package zeromq python-zmq
+        elif is_ubuntu; then
+            uninstall_package libzmq1 python-zmq
+        elif is_suse; then
+            uninstall_package libzmq1 python-pyzmq
+        else
+            exit_distro_not_supported "zeromq installation"
+        fi
+    fi
+}
+
 # install rpc backend
 function install_rpc_backend() {
     if is_service_enabled rabbit; then