fixed out of bitcoins; cleanup

lib/routes.js

@@ -57,7 +57,11 @@ var trade = function (req, res) {
 var send = function(req, res) {
   var fingerprint = req.connection.getPeerCertificate().fingerprint;
   _trader.sendBitcoins(fingerprint, req.body, function(err, txHash) {
-    res.json({err: err, txHash: txHash});
+    res.json({
+      err: err && err.message, 
+      txHash: txHash, 
+      errType: err && err.name
+    });
   });
 };