Unskip the tests affected by warlock 1.3.0

1) This reverts commit 044a46e
which was broken by warlock 1.3.0

Change-Id: Ia286d9394586884018c4e62cf581e39a809f5545

Author: stevemar

functional/tests/image/v2/test_image.py

@@ -13,8 +13,6 @@
 import os
 import uuid
 
-import testtools
-
 from functional.common import test
 
 
@@ -68,7 +66,6 @@ def test_image_metadata(self):
         raw_output = self.openstack('image show ' + self.NAME + opts)
         self.assertEqual(self.NAME + "\na='b', c='d'\n", raw_output)
 
-    @testtools.skip("skip until bug 1596573 is resolved")
     def test_image_unset(self):
         opts = self.get_opts(["name", "tags", "properties"])
         self.openstack('image set --tag 01 ' + self.NAME)