Make the devices list a vector

It's the suggested data type to use according to:
https://marcmutz.wordpress.com/effective-qt/containers/

interfaces/devicesmodel.h

@@ -83,7 +83,7 @@ private:
     void clearDevices();
 
     DaemonDbusInterface* m_dbusInterface;
-    QList<DeviceDbusInterface*> m_deviceList;
+    QVector<DeviceDbusInterface*> m_deviceList;
     StatusFlags m_displayFilter;
 };