Add support for mobile android browser

I believe there's a bug with OS detection. The old default browser on Android sends a useragent string like this: "Mozilla/5.0 (Linux; U; Android 4.0.4; en-us; GT-I9300 Build/IMM76D) AppleWebKit/534.30 (KHTML, like Gecko) Version/4.0 Mobile Safari/534.30", and the inclusion of Safari trips detect into thinking its Safari. 

My change adds "Safari" to the the list skipped words in Safari::checkWords and creates a new OS subclass to detect the AndroidBrowser.