devstack: clone Manila client only if marked to

Currently, Manila's devstack plugin clone manilaclient. Some projects
depend on Manila but would like to install packaged manilaclient.
Clone the manilaclient only if it was marked to be used from git

Change-Id: Ia8e726b9358f6901c172a31f638a59eba523e0fa
Depends-On: I94d2f143159b60c4f8693e35fe844bc1e411e580

devstack/plugin.sh

@@ -672,10 +672,20 @@ function _install_nfs_and_samba {
     fi
 }
 
+# install_manilaclient - Collect source and prepare
+#   In order to install from git, add LIBS_FROM_GIT="python-manilaclient"
+#   to local.conf
+function install_manilaclient {
+    if use_library_from_git "python-manilaclient"; then
+        git_clone $MANILACLIENT_REPO $MANILACLIENT_DIR $MANILACLIENT_BRANCH
+        setup_develop $MANILACLIENT_DIR
+    else
+        pip_install python-manilaclient
+    fi
+}
+
 # install_manila - Collect source and prepare
 function install_manila {
-    git_clone $MANILACLIENT_REPO $MANILACLIENT_DIR $MANILACLIENT_BRANCH
-    setup_develop $MANILACLIENT_DIR
     setup_develop $MANILA_DIR
 
     if is_service_enabled m-shr; then
@@ -928,6 +938,8 @@ function install_libraries {
 
 # Main dispatcher
 if [[ "$1" == "stack" && "$2" == "install" ]]; then
+    echo_summary "Installing Manila Client"
+    install_manilaclient
     echo_summary "Installing Manila"
     install_manila
     set_cinder_quotas

doc/source/devref/development-environment-devstack.rst

@@ -59,6 +59,12 @@ Enable the manila plugin adding the following line to the end of the local.conf
 
     enable_plugin manila https://github.com/openstack/manila
 
+If you would like to install python-manilaclient from git, add to local.conf:
+
+::
+
+    LIBS_FROM_GIT="python-manilaclient"
+
 Manila UI
 `````````