Feature/book 774 parse docdata errors

- Catch payment errors at adapters.
- Add some criteria in payments_mock to throw errors.
- Catch and refine errors in payments view.
- Show errors in Ember donation modal.
- Write tests to check that mock errors appear in API.

Mind you! 
Test for PaymentsMock status changes are disabled for now. @aethemba has some code that will fix those.
I've re-added the code. Then we can decide later ;-)