Allow selecting time zone for the clock widget

[gitmatt19]

It would be great if we could set the time zone on the clock widget.

[lambdadog]

I've been looking into this as I'm in need of a clock widget for a different timezone, and the biggest barrier to this is that widget configuration is global -- while modifying the configurator for the widgets to include time zone would be fairly trivial since you can simply setTimeZone on a TextClock, if you had multiple of the same type of widget they would all use the same timezone, which in many obvious usecases of being able to create clock widgets with different timezones quite misses the point.