Added in Windows Phone 8, Windows 8 Touch, MSIE 10, and a few tests

Hi! I've been doing a lot of mobile work and we are now supporting Windows Phone 8 and Windows 8. I got to know the user agent strings for browsers running on these devices. I love the gem and added in Windows Phone 8, IE 10, and Windows 8 Touch user agent checks + tests.

Thanks for the great gem!