Modify to last tests with ping

Drone/client.py

@@ -47,6 +47,8 @@ class Client(object):
         global active_client
         active_client = self
 
+        self._last_ping_time = 0
+
     def load_config(self):
         self.config.read(self.config_path)
 
@@ -188,6 +190,9 @@ class Client(object):
     def _process_connections(self):
         while True:
             events = self.selector.select(timeout=1)
+            if time.time() - self._last_ping_time > 5:
+                self.server_connection.send_message("ping")
+                self._last_ping_time = time.time()
             # logging.debug("tick")
             for key, mask in events:  # TODO add notifier to client!
                 connection = key.data