Calendar rebase

This replaces #1281.

Fixed unit tests and cleaner history based on Scott's rebase. Unit tests work in latest FF and Chrome but still fail via grunt. @jzaefferer You mentioned an upcoming improvement for asycTests?
_hoverable does not seem to work. Seems @tjvantoll had this issue before as there was a comment, see here: https://github.com/fnagel/jquery-ui/commit/64177380231f600f4fccd46ef8bb6e9a401131c9#diff-563a5392a566d1a29a68b1b5a37c4cb6R74

I've changed it to on, but I'm not sure if it's really a better solution. Take a look when I updated the PR.