Timepicker is required by default without the option to change it

[gabguy]

I need the uib-timepicker element on a form without it being a required field and that is not possible now.
Please set an option to set the required (or ng-required) of the timepicker

[icfantv]

Closing in favor of #5957 as this will result in a complete rewrite of the widget, addressing all the outstanding issues.