Bug 1054178 - [Gaia][calendar] support 24 hour time format

@millermedeiros , How do you think about this change?
We do this because before this change we could not render a template correctly in another template. For example, we could not do
```
var MonthsDay = Calendar.Template.create({
  event: function() {
    Calendar.Templates.DateSpan.time.render({
      time: new Date(),
      format: 'shortTimeFormat'
    });
  }
});
```
before this change. The `data` will just be overwrited.