902973 - [SMS][MMS] Intermittent TEST-UNEXPECTED-FAIL in notification_test.js r=gnarf

https://bugzilla.mozilla.org/show_bug.cgi?id=902973

- Clean up
- Migrate to sinon.spy
- Use mocks as spy targets
- Assert on spy intel instead of mock properties
- Simpify mocks
- Ensure Threads tests start with hash = '';
- Remove from blacklist

Signed-off-by: Rick Waldron <waldron.rick@gmail.com>