Match new Tor Browser Bundle User-Agent in is_likely_tor_browser
We have:
var TBB_UA = "Mozilla/5.0 (Windows NT 6.1; rv:10.0) Gecko/20100101 Firefox/10.0";
My User-Agent is now:
Mozilla/5.0 (Windows NT 6.1; rv:17.0) Gecko/20100101 Firefox/17.0
Let's match either.