Updated server shutdown timer logic

Will follow the following rules

+ send a message initially
+ send a message every 20 mins
+ send a message every min when time <= 5

Updated client popup

Updated client to close any previous popups and bring up a new one.

NEEDS TO BE TESTED

added missing include

Added delete on close

servatrice/src/servatrice.h

@@ -120,6 +120,7 @@ private:
 	QString shutdownReason;
 	int shutdownMinutes;
 	QTimer *shutdownTimer;
+    bool isFirstShutdownMessage;
 	
 	mutable QMutex serverListMutex;
 	QList<ServerProperties> serverList;