Added an optional unique field to Album and checked that duplicates are detected.
Forgot to add the ref field to the field list.
More complex test case.
Fixed the validation for optional fields that have a value.
Merge pull request #1455 from ericbuehl/master

don't implicitly import provider.oauth2
Add SEARCH_PARAM and ORDERING_PARAM to settings

Fixes #1434
Merge pull request #1459 from linovia/bugfix/optional_unique_validation

Unique constraint are validated even if the field is optional.
Use six to reload module
Merge pull request #1460 from inglesp/issue1434

Add SEARCH_PARAM and ORDERING_PARAM to settings
Pin pillow to 2.3.0
Don't barf if PIL is not installed.
Add Django 1.7 to tox
Reintroduced url arguments in the urls for the tests.
Merge pull request #1463 from linovia/bugfix/old_request_factory_url_arguments

Reintroduced url arguments in the urls for the tests.