Bug 882751 - Tapping in the center of the clock doesn't work as expected r=ianliu

https://bugzilla.mozilla.org/show_bug.cgi?id=882751

- Reorder digital-clock HTML elements to match analog-clock layout
- Creates explicit object for all timeouts
- Adds `container` to list of lazy init'ed elements
- Removes the unused `this.digitalClockBackground` element
- Consolidates init and initClockface, removes initClockface
- Ensures handleEvent is called with bound handlers
- removes unnecessary nested setTimeout function calls
- Consolidates logic from showAnalogClock, showDigitalClock and show
- Removes showAnalogClock, showDigitalClock
- Defines single pattern for clock face display
- Includes tests for support of Clock.show() and ClockView.handleEvent->show
- Adds mock_alarm_list, mock_asyncstorage
- Ensure that a clock face default always shows, no matter what.
- Request stored clock face mode as early as possible
- Ensure that clock face mode is updated if default doesn't match stored.
- Simplify the clock face rendering tests

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