Update Readme.txt
Update Readme.txt

Add Gitter Chat reference to Nuget readme
Add yet another reference to installing Visual C++ 2013
wangzheng888520/CefSharp,jamespearce2006/CefSharp,jamespearce2006/CefSharp,wangzheng888520/CefSharp,dga711/CefSharp,Livit/CefSharp,dga711/CefSharp,wangzheng888520/CefSharp,Livit/CefSharp,Livit/CefSharp,jamespearce2006/CefSharp,wangzheng888520/CefSharp,dga711/CefSharp,jamespearce2006/CefSharp,dga711/CefSharp,jamespearce2006/CefSharp,Livit/CefSharp