Avoid checking for table privacy when not using table maps

See #147

lib/cartodb/server_options.js

@@ -558,9 +558,13 @@ module.exports = function(){
                 }
 
                 if ( ! signed_by ) {
-                  // request not authorized by signer, continue
-                  // to check map privacy
-                  return null;
+                  // request not authorized by signer,
+                  // continue to check table privacy,
+                  // if table was given
+                  if ( req.params.table ) return null;
+                  // otherwise return no authorization
+                  callback(err, null);
+                  return;
                 }
 
                 // Authorized by "signed_by" !