use networkname from txp

lib/server.js

@@ -460,9 +460,9 @@ CopayServer.prototype.getTx = function(opts, cb) {
   });
 };
 
-CopayServer.prototype._broadcastTx = function(txp, networkName, cb) {
+CopayServer.prototype._broadcastTx = function(txp, cb) {
   var raw = txp.getRawTx();
-  var bc = this._getBlockExplorer('insight', networkName);
+  var bc = this._getBlockExplorer('insight', txp.getNetworkName());
   bc.broadcast(raw, function(err, txid) {
     return cb(err, txid);
   })
@@ -511,7 +511,7 @@ CopayServer.prototype.signTx = function(opts, cb) {
         if (err) return cb(err);
 
         if (txp.status == 'accepted') {
-          self._broadcastTx(txp, wallet.getNetworkName(), function(err, txid) {
+          self._broadcastTx(txp, function(err, txid) {
             if (err) return cb(err, txp);
 
             txp.setBroadcasted(txid);