Graph API revert to point to latest 14.0

Summary: Graph API latest version is now at 14.0

Reviewed By: SergioGuerreroFB

Differential Revision: D38142989

fbshipit-source-id: 104bf06cf137288976a0ab2ad5859fff94905c58

Author: zenlita

Facebook.Unity/Constants.cs

@@ -45,7 +45,7 @@ internal static class Constants
         public const string OnGroupJoinCompleteMethodName = "OnJoinGroupComplete";
 
         // Graph API
-        public const string GraphApiVersion = "v14.1";
+        public const string GraphApiVersion = "v14.0";
         public const string GraphUrlFormat = "https://graph.{0}/{1}/";
 
         // Permission Strings