Added test stubs for Organizations.

Test stubs for most CRUD positive/negative scenarios have been reviewed
and ACKed by QE and DEV teams. Note that ``tests/cli/test_org.py``
already has some tests that overlap with the stubbed tests, but since
they are not data-driven, they should most likely get removed as tests
are automated (this will be left as an exercise to the test
implementer).

Though some of the tests are currently "blocked" on several issues, both
Bugzilla and Redmine, the tests can still be written and should fail
until said issues are handled and fixed upstream.