AMD support

http://wiki.jqueryui.com/w/page/66995889/AMD-Support

- [x] Remove build from Grunt
- [x] Remove "globals" from all files
- [x] [Script to rename all files](https://gist.github.com/jzaefferer/893fcf70b7eebc1dc271)
- [x] Actually rename all files, removing the "jquery.ui." prefix, before landing this PR
- [x] Copy updated i18n files to datepicker demos

After merging to master:
- [ ] Expose `$.Widget`.
- [ ] Split core into multiple files.
- [ ] Bring back support for testing minified files in unit tests. Needs to use actual build output.
- [ ] Use an AMD loader for tests.

Skip
- Handle CSS dependencies - comments-based as in jQuery Mobile, see https://github.com/jquery/download.jqueryui.com/issues/178