Bug 904220 - [Clock] Unit tests should not create actual alarm records

https://bugzilla.mozilla.org/show_bug.cgi?id=904220

- Reorders require files alphabetically
- Adds Mocks:
    - mock_alarm_list.js
    - mock_alarm_manager.js
    - mock_navigator_mozl10n.js
- Update tests to use actual markup as fixture
- Update tests to use the same mocha API as other tests
- Use mocks instead of creating real alarm records
- Use sinon sandbox features

Signed-off-by: Rick Waldron <waldron.rick@gmail.com>