Remove redundant import alias

This patch remove redundant import aliases and add pep8 hacking function
to check no redundant import aliases.

Co-Authored-By: Dao Cong Tien <tiendc@vn.fujitsu.com>

Change-Id: I3207cb9f0eb4b4a029b7e822b9c59cf48d1e0f9d
Closes-Bug: #1745527

watcher/notifications/exception.py

@@ -16,7 +16,7 @@ import sys
 import six
 
 from watcher.notifications import base as notificationbase
-from watcher.objects import base as base
+from watcher.objects import base
 from watcher.objects import fields as wfields