Replace assertTrue(isinstance()) with assertIsInstance()
Replace assertTrue(isinstance()) with assertIsInstance()

Some of tests use different method of assertTrue(isinstance(A, B)) or
assertEqual(type(A), B). The correct way is to use assertIsInstance(A,
B) provided by testtools.

Change-Id: Id23bbaf4bfc2795022b2871709097d50d8122525
Closes-Bug: #1268480

SauloAislan/ironic,pshchelo/ironic,openstack/ironic,openstack/ironic,pshchelo/ironic,SauloAislan/ironic