filter widget - first commit

@uGoMobi, @arschmitz

Through with testing. Everything passes on my machine (tested functions on FF, Chrome, IE8 so far Qunit on FF, Chrome)

Some notes:
- Latest demo [here](http://www.franckreich.de/jqm/filter/demo.html)
- I have not removed any of the listview filter extension files
- Tests: I sporadically get an error `self._getFilterableItems()` is not defined. Still chasing this, but makes no sense to me, as it's defined in the function preceding the function that calls it.
- Tests: As the filter now has a 300ms delay (option?), I needed to `setTimeout` quite a bit in the tests. If that's not the way to go, let me know and I will amend.
- Tests: I tested `ul, table, div, controlgroup, select, p, span`. Any others I should add and all else, please also let me know.