On token verification failure return error, reason and stop processing.

This was broken with commit c1fb1a7def, which splits the result in order to print the error reason and in case of error was not returning the error and the message to prosody internals.

resources/prosody-plugins/mod_auth_token.lua

         if (res == false) then
             log("warn",
                 "Error verifying token err:%s, reason:%s", error, reason);
+            return res, error, reason;
         end
 
         local customUsername