title: phantomjsdriver how to add user-agent?
body: <p>i'm using phantomjsdriver 1.8.1 for .net (C#) 
   <a href="http://www.nuget.org/packages/phantomjs.exe/" rel="nofollow">http://www.nuget.org/packages/phantomjs.exe/</a> and wonder how to add user-agent firefox before loading the web content </p>