Tokens API additional models

1. Added a test data file and more unit tests for the tokens api access model.
2. Completed fleshing up all models included in the tokens api access model.
3. Finished testing the tokens api access model.
4. Renamed the tests folder to metatests.
5. Completed fleshing up all tokens api response models.
6. Fixed code review issues.
7. Refactored reponses models and added a new test in access_test.py.
8. Rebased changes and uploaded a new patch set.
9. Fixed reviewer comment - made access.json in a more readable format.

Change-Id: Ifb5c03a4de622dc0ed29485fc26e354632c777c3
Merge "Tokens API additional models"