Bug 1023735 - [Settings] Support new time format settings

- change langauge -> update timeformat
- add default settings and l10n properties
- change timeZone -> redraw time field with user pref
- change time/dateFormat -> update time/date field with user pref
- change date/time field -> correct set date/time
- change date field -> redraw dateFormat with user pref
- add navigator.mozHour12 API shim
I think including `DateTime` module here makes sense but it should not expose a new method for language panel. Making `DateTime` update itself depending on the language settings is more robust.