updated error handling on all mocha tests

- switch to using catch
- added error handling where missing
Merge pull request #2692 from cobbspur/newerror

updated error handling on all mocha tests
Proper endpoints for persistent notifications

closes #2637
- Add new get API route for all notifications
- Wrap API responses to comply with JSON-API
- Add new tests / adjust fixtures
- Adjust all occurences of passive notifications