Add a devstack plugin for shade

Install shade with devstack. This is really simple because there's not
really any configuration needed.

Change-Id: Ic5962bfb0e25d592d50458f32a21ac612479447c

devstack/plugin.sh

@@ -0,0 +1,54 @@
+# Install and configure **shade** library in devstack
+#
+# To enable shade in devstack add an entry to local.conf that looks like
+#
+# [[local|localrc]]
+# enable_plugin shade git://git.openstack.org/openstack-infra/shade
+
+function preinstall_shade {
+    :
+}
+
+function install_shade {
+    if use_library_from_git "shade"; then
+        # don't clone, it'll be done by the plugin install
+        setup_dev_lib "shade"
+    else
+        pip_install "shade"
+    fi
+}
+
+function configure_shade {
+    :
+}
+
+function initialize_shade {
+    :
+}
+
+function unstack_shade {
+    :
+}
+
+function clean_shade {
+    :
+}
+
+# This is the main for plugin.sh
+if [[ "$1" == "stack" && "$2" == "pre-install" ]]; then
+    preinstall_shade
+elif [[ "$1" == "stack" && "$2" == "install" ]]; then
+    install_shade
+elif [[ "$1" == "stack" && "$2" == "post-config" ]]; then
+    configure_shade
+elif [[ "$1" == "stack" && "$2" == "extra" ]]; then
+    initialize_shade
+fi
+
+if [[ "$1" == "unstack" ]]; then
+    unstack_shade
+fi
+
+if [[ "$1" == "clean" ]]; then
+    clean_shade
+fi