NuGet.config - Add appveyor cef-binary project feed

cef-binary tagged releases are now pushed to this feed
(Myget still needs to be updated to pull packages from this feed)

Author: amaitland

NuGet.config

@@ -5,5 +5,6 @@
     </activePackageSource>
   <packageSources>
     <add key="cefsharp-myget" value="https://www.myget.org/F/cefsharp/" />
+	<add key="cefsharp-appveyor" value="https://ci.appveyor.com/nuget/cef-binary-ci" />
   </packageSources>
 </configuration>