AbstractFormat: handle null owners correctly (mainly for tests)
controller.Abstracts: complete the implementation
GCAAuth: return JSON in exHandlerJSON (and fix status codes)
[test] AbstractCtrlTest: Tests for the controller.Abstracts

Currently fails the test for "update". Fix for this comes separately
Merge pull request #47 from gicmo/AbstractController

Complete controller.Abstracts plus tests for it

OK, only testUpdate fails (as mentioned above)