New Windows 8 Store App Support

Basically it covers only the SCAN method. The details of the strategy used can be found at: http://vinnylinck.tumblr.com/post/88402574921/windows-8-store-apps-javascript-and-barcode-scanner

It works for WIndows 8 and Windows 8.1 Store Apps. I testes  with some LeNovo devices (tablets) and my Vostro notebook.

Anything else, just let me know (and if finding any issue as well). Feel free to improve this piece of code.