Add backward compatibility with python-cinderclient<=1.5.0

python-cinderclient<=1.5.0 CLI module searches extensions with
'python_cinderclient_ext' suffix in PYTHONPATH.

brick_python_cinderclient_ext/__init__.py

@@ -0,0 +1,13 @@
+#    Licensed under the Apache License, Version 2.0 (the "License"); you may
+#    not use this file except in compliance with the License. You may obtain
+#    a copy of the License at
+#
+#         http://www.apache.org/licenses/LICENSE-2.0
+#
+#    Unless required by applicable law or agreed to in writing, software
+#    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+#    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+#    License for the specific language governing permissions and limitations
+#    under the License.
+
+from brick_cinderclient_ext import *  # noqa

setup.cfg

@@ -22,6 +22,7 @@ classifier =
 [files]
 packages =
     brick_cinderclient_ext
+    brick_python_cinderclient_ext
 
 [build_sphinx]
 source-dir = doc/source