Add a TimedEvent to cancel the connection to a server after 5 seconds

src/network/socket_handler.hpp

@@ -85,6 +85,11 @@ public:
    * Close the connection, remove us from the poller
    */
   void close();
+  /**
+   * Called by a TimedEvent, when the connection did not succeed or fail
+   * after a given time.
+   */
+  void on_connection_timeout();
   /**
    * Called when the connection is successful.
    */