Provide region name while initialize clients

Add new option 'region_name' to config for each client section.

Change-Id: Ifad8908852f4be69dd294a4c4ab28d2e1df265e8
Closes-Bug: #1787937

watcher/conf/monasca_client.py

@@ -29,7 +29,10 @@ MONASCA_CLIENT_OPTS = [
                default='internal',
                help='Type of interface used for monasca endpoint.'
                     'Supported values: internal, public, admin'
-                    'The default is internal.')]
+                    'The default is internal.'),
+    cfg.StrOpt('region_name',
+               help='Region in Identity service catalog to use for '
+                    'communication with the OpenStack service.')]
 
 
 def register_opts(conf):