The 12/24 hour format ui tests have race condition issues.

Hi Miller,

The answer is no, if the 24h format is the default setting.

But at mean time, I think we might need to find a simple way to fix http://bugzil.la/1061135.
For sure, we also need to find a lone term solution to deal with it.

The another solution is that we could only do somethings in the test code, like
```
client.waitFor(function() {
  return day.sideBarHours[0].text() === '12 AM';
});
```
to instead of [1]. Then, we don't need to change the calendar app code.

Or Miller has other idea for this issue?

Thanks.

[1] https://github.com/mozilla-b2g/gaia/blob/master/apps/calendar/test/marionette/day_view_test.js#L297