Loading binaries via xhr in ie8, adding 'timeout' support

2 extra features:

- fixed issue that arose when attempting to preload a binary file via xhr in IE8
- added a `timeout` property on html5Preloader objects. if set, will cause an 'error' event for any file that takes longer than `timeout`ms to load.

Just noticed a new branch on your project -- if that's still going on, will happily re-submit there as well.