Add support for jQuery 'one' method

* Add 'one' method that inserts extra arg and passes to 'on'.
* Update parse of arguments in 'on' so 'one' arg is passed to jQuery (has this got too hairy?).
* Add control test for 'on'.
* Add tests for new 'one' method.

I had a use case for this in a component in TweetDeck. Trivial to work around of course, but nice if it just worked for people familiar with it from jQuery?