Detect localStorage, smart unique, easy synch require, fix

Hi, Awesome product btw!

I wanted to use it with requirejs and I've started to add features. So if you like them add them. The changes are:
* Detect if browser support localStorage
* Add smart unique detection - if checksums looks like "url":"md5_of_file" and this checksums are loaded dynamicly the result will be "recache file if it was changed"
* I have fixed the problem in basket.clear(). If crashes when try to clear loaded url contained "basket-" (i.e. "basket-require.js")
* make a function synchRequire for easier usage

I am not a unit-test-guy so I have no test, but your tests passed. I have an example of usage here: 
https://github.com/peterdenev/requirejs-basketjs/tree/master/example (in php file)

Thanks