Change assertTrue(isinstance()) by optimal assert
Change assertTrue(isinstance()) by optimal assert

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: I79ae67c2509cfeac6e7c53257dc4f26715fb9012
Closes-bug: #1268480

ionutbalutoiu/ironic,dims/ironic,NaohiroTamura/ironic,dims/ironic,SauloAislan/ironic,pshchelo/ironic,openstack/ironic,openstack/ironic,SauloAislan/ironic,NaohiroTamura/ironic,pshchelo/ironic,bacaldwell/ironic,devananda/ironic,bacaldwell/ironic,ionutbalutoiu/ironic