Datepicker using Globalize 1.x

:boom: WIP...

The goal is to have Datepicker working with Globalize 1.x.

Depends on
- [ ] https://github.com/jquery/jquery-ui/pull/1316 `fnagel:calendar-value-pr`;

Todo
- [ ] Destroy translation data (weekHeader, prevText, nextText , datePickerRole, currentText). Create user options instead;
- [ ] Move `external/date.js` into `ui/` (see #1260 (comment));
- [ ] Fix RTL LTR direction;