Fix for a bug

Knew I was going to forget something somewhere.  Fixes #134.  Thanks for the report!

lib/coins/xmr.js

@@ -80,7 +80,7 @@ function Coin(data){
             reserve_size: 17,
             wallet_address: walletAddress
         }, function(body){
-            return callback(err, body);
+            return callback(body);
         });
     };