VoIP Support for Webform Date Component

This is my first go-around at support for the webform date component. Still on the to-do list are:

- Figure out why the submission won't save this component. Something having to do with the format of the response I would guess. I've tried some various methods (they are commented out in the patch). I'll look at this again with a fresh head sometime.
- Validation of date vs. allowed values