Add test for OPTIONS requests

[mattdowdell]

HTTP OPTIONS request support has been implemented to support behaviour exhibited by browsers (OPTIONS followed by the actual request), but no testing has yet been implemented. See app/controllers/v1/api_controller.rb#options for implementation.

[mattdowdell]

Update: Test added in test/controllers/v1/tests_controller_test.rb#options, although test coverage analysis claims it does not work correctly. This should be investigated further.