Replace assertEqual(None, *) with assertIsNone

From python 2.7 onwards, some new method such as assertIsNone
equivalent to the assertEqual,this will simplify the number of
parameters.

I am looking for all the assert method, which can be updated and
renewed,and changed the place where I think they can change.
These changes should be harmless

refer to [1] for more information

[1]:https://docs.python.org/2.7/library/unittest.html#unittest.TestCase.assertIsNone

Closes-Bug #1618434
Change-Id: I67db37a0f7561c638d5bb8f2ccd894fa07f6109e

tests/integration/tests/dns/conversion.py

@@ -96,10 +96,10 @@ class WhenCreatingAnEntryForAnInstance(unittest.TestCase):
                                    FLAGS.dns_domain_name)
         self.assertEqual(expected_name, entry.name,
                          msg="Entry name should match - %s" % entry.name)
-        self.assertEqual(None, entry.content)
+        self.assertIsNone(entry.content)
         self.assertEqual("A", entry.type)
         self.assertEqual(FLAGS.dns_ttl, entry.ttl)
-        self.assertEqual(None, entry.priority)
+        self.assertIsNone(entry.priority)
         self.assertEqual(FLAGS.dns_domain_name, entry.dns_zone.name)
         if not entry.dns_zone.id:
             self.fail(msg="DNS Zone Id should not be empty")

tests/integration/tests/volumes/driver.py

@@ -206,7 +206,7 @@ class AddVolumeFailure(VolumeTest):
         Make call to FAIL a prov. volume and assert the return value is a
         FAILURE.
         """
-        self.assertEqual(None, self.storyFail.volume_id)
+        self.assertIsNone(self.storyFail.volume_id)
         name = "TestVolume"
         desc = "A volume that was created for testing."
         self.storyFail.volume_name = name
@@ -257,7 +257,7 @@ class AddVolume(VolumeTest):
     @time_out(60)
     def test_add(self):
         """Make call to prov. a volume and assert the return value is OK."""
-        self.assertEqual(None, self.story.volume_id)
+        self.assertIsNone(self.story.volume_id)
         name = "TestVolume"
         desc = "A volume that was created for testing."
         self.story.volume_name = name