Add Identity v3 test structure

* Split identity/fakes.py for v2_0 and v3
* Split identity/test_identity.py for v2_0 and v3

Change-Id: I6e536b6a130fc556dbd7dcf9f2e76d939ca1bc1c
Identity user v3 tests

* Add user v3 tests
* Fix issues in commands with enable/disable
* Make commands and tests more consistent between versions
* Make formatting and comments more consistent

Change-Id: Icaa7fe23519b1b41f552371bb7d1814d2bbee000
Identity project v3 tests

* Add project v3 tests
* Fix issues in commands with enable/disable
* Make commands and tests more consistent between versions
* Make formatting and comments more consistent

Change-Id: If4a64ca64aa6f2de59550174e386d76ad6e418d3
Identity role v3 tests

* Add role v3 tests
* Fix issues in commands with enable/disable
* Make commands and tests more consistent between versions
* Make formatting and comments more consistent

Change-Id: I78627278269aa8c5a63fcee6ea8c3192db443347
Identity service v3 tests

* Add service v3 tests
* Fix issues in commands with enable/disable
* Make commands and tests more consistent between versions
* Make formatting and comments more consistent

Change-Id: I841b6ab65e4a19ba4f3f712e1dc997e345f9850f
Merge branch 'test-clientmanager' into dt-test
Merge branch 'test-idv3-base' into dt-test
Merge branch 'test-idv3-project' into dt-test
Merge branch 'test-idv3-user' into dt-test
Merge branch 'test-idv3-role' into dt-test
Merge branch 'test-idv3-service' into dt-test