* Relocate ansible-test self tests outside package.
We don't want to include the tests for verifying ansible-test within the ansible-test package.
* Add `test/ansible_test/` to classification.py.
* Fix test invocation.
* Relocate tests in MANIFEST.in.
* Improve package-data sanity test error checking.
* Only use includes for ansible-test in MANIFEST.in.
* Improve readability of MANIFEST.in.
