Set client module __version__

According to PEP 396, the version of client library
should be set in xxxclient.__version__, that help
python-openstackclient command "module list" to get
the right plugin module versions.

Change-Id: I932287726c5b0a8638c6ad72171e98181867d88f
Partial-Bug: #1662058

designateclient/__init__.py

@@ -0,0 +1,19 @@
+#   Copyright 2017 Huawei, Inc. All rights reserved.
+#
+#   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 designateclient import version
+
+
+__version__ = version.version_info.version_string()

designateclient/tests/test_designateclient.py

@@ -17,10 +17,11 @@ test_designateclient
 Tests for `designateclient` module.
 """
 
+import designateclient
 from designateclient.tests import base
 
 
-class DummyTestCase(base.TestCase):
+class ClientTestCase(base.TestCase):
 
-    def test_dummy(self):
-        pass
+    def test_module_version(self):
+        self.assertTrue(hasattr(designateclient, '__version__'))