Class Credentials not define __ne__() built-in function

Class Credentials defines __eq__() built-in function, but does
not define __ne__() built-in function, so self.assertEqual works
but self.assertNotEqual does not work at all in this test case in
python2. This patch fixes it.

Change-Id: I2c0d9d6202d64de57700ceb7c15db8ed3ad7e8ff
Closes-Bug: #1586268
1 file changed