Minion alert disconnect

Enables the minion to detect if the connection to the master is still alive. If the connection is down, an event is fired which is caught in the minion main loop. It has to be explicitly enabled in the minions config.

Handling the __master_disconnect event is only POC for now. I'm not sure yet how to make it as flexible as possible to enable everyone to configure it to their needs later. Its primary goal is to make the minion able to work with multiple master and have the minion jump to the next master if the current master dies.