Utility Function to cache YQL Requests in LocalStorage (for webOS)

Usage:

yqlcache.get({
	yql: "select * from rss where url='http://feeds.feedburner.com/mobile-tuts-summary",
	id: 'mobile-tuts-summary',
	cacheage: (60*60*1000),
	callback: this.parseResult.bind(this)
});

TODO: handle failed YQL Requests

Returns an object with object.type = 'freshcache' or 'cached' and object.data = Data from YQL Query (JSON)

Based on https://github.com/codepo8/yql-localcache by Christian Heilmann (@codepo8)