Issue #37: Adjust timepicker position on open to remain inside the window.

Hi wvega, here is a proposed solution for the case where the timepicker is near the bottom of the window and may not be visible. This references issues #37 which I reported earlier today.

Please let me know if there should be any other steps for this pull request, or if I can add test cases etc.

By the way, I noticed that the paths to jquery in the visual test cases didn't match the repository layout. Is there a build step that moves them? (the jquery files are in ../resources/jquery/ but the visual test cases reference ../../external/ which doesn't exist..