Updated the config sample file generation command

Following the update of the project requirements, we should now
use the oslo.config namespace of oslo.log when generating ou
Watcher config sample file.

Change-Id: I7a1f3d555534b40c041b7f042f19fae231b7e80c
Closes-Bug: #1518297

watcher/common/policy.py

@@ -18,7 +18,7 @@
 from oslo_concurrency import lockutils
 from oslo_config import cfg
 
-from watcher.openstack.common import policy
+from oslo_policy import policy
 
 _ENFORCER = None
 CONF = cfg.CONF