Google Chrome support through the deviceorientation event

Hey there Alex!

I stumbled on your library through some googling and liked it! Only thing is that I use the Google Chrome mobile browser almost exclusively so I checked out some methods to implement shake detection in HTML5 and hacked it together using the deviceorientation event.

I'm not sure if you want to merge it into your repo, both because my code probably isn't very clean and maybe you don't want to have a deviceorientation hack in your library :)

In any case I decided to do a pull request anyways just in case you like the code and decide you want it. Feel free to alter it in any way if you like.

Cheers,
Kristján.