Leading zeros for time display.

Time is now shown with leading zeros.

7:9 is now 07:09
10:5 is now 10:05
Actually, now that I think about it, you should revert this back entirely. This changes the type (and value) of `gt.hours` and `gt.minutes`, which used to be numbers but are now strings. You should change the display, not the data, i.e. the point where `gt.hours` and `gt.minutes` are displayed in the text box should be adjusted by this.