Replaced try/catch with a callback

Done this to follow ws error-handling best practices (see https://github.com/einaros/ws/blob/master/README.md).

Author: sarfata

lib/ddp-client.js

@@ -77,13 +77,10 @@ DDPClient.prototype._recoverNetworkError = function() {
 ///////////////////////////////////////////////////////////////////////////
 // RAW, low level functions
 DDPClient.prototype._send = function(data) {
-  try {
-    this.socket.send(JSON.stringify(data));
-  }
-  catch (error) {
-    // The socket will throw a socket-error event and we will recover.
-    // This message will be lost however.
-  }
+  this.socket.send(JSON.stringify(data), function(error) {
+    // This callback to avoid an exception being thrown.
+    // if an error happened, the socket will throw an event and we will recover.
+  });
 };
 
 // handle a message from the server

test/ddp-client.js

@@ -98,6 +98,7 @@ describe("Network errors", function() {
 
     ddpclient.call('aServerMethod', [42], callCB);
 
+    // First of all, the previous call should not throw anything.
     // The method callback should not be called
     // The socket-error event should not be triggered now
     // (but it will be triggered later by the socket)