feat(timezone): Support ng-model-options timezone

[mchapman]

Introduce support for ng-model-options timezone

Resolves#88, specifically #88 (comment)

[alexanderchan]

Thanks!

[MichaelBuen]

Tried ng-model-options="{timezone: '+10:00'}" an Australia/Sydney timezone

On initial load, the model is working correctly, e.g., April 22 2017 00:00 is April 21 2017 14:00. However, whenever a new date is selected, e.g., April 5 2017, the model become April 4 2017 12:00 instead of April 5 2017 14:00, then when selecting another date say April 25 2017, the model become April 25 2017 10:00 AM. The time part always decrement by two hours whenever a new date is selected.

Other detail, I'm in Asia/Manila, which is +8:00

[MichaelBuen]

This feature does not work.

ng-model-options={timezone: timezoneHere} works on HTML5's date input <input type='date'/>. Cannot use that though, need UI consistency with existing system, need to use the jQuery-based datepicker for angular.

@mchapman could this be fixed?