Add plugin manifest file
Update jQuery versions used in tests

- Remove versions older than 1.7
- Replace 1.8.0 with 1.8.3
- Add 1.9.1
Fix comments related to setting the hint
Use the latest version of QUnit
Update tests to work with the latest QUnit

- Use equal() instead of equals()
Remove Firefox option click workaround

I wasn't able to reproduce the issue (even on as old version of Firefox as
2.0), so it's possible that this was fixed at some point when I refactored the
plugin code.
Make the plugin compatible with jQuery 1.9
Delete Makefile
Add Gruntfile
Copyright year++
Update the included version of jQuery to 1.9.1