refresh time for all devices + schema fixes (#305)

* refresh for all :-)
remove dups

* - integrate refresh leds for all devices
- fix schemas for led devices

* add minimum for rewrite time

* rewriteTime: add missing info in config examples

libsrc/leddevice/LedDeviceFile.cpp

@@ -21,7 +21,10 @@ bool LedDeviceFile::init(const QJsonObject &deviceConfig)
 	{
 		_ofs.close();
 	}
-	
+
+	_refresh_timer_interval = 0;
+	LedDevice::init(deviceConfig);
+
 	std::string fileName = deviceConfig["output"].toString("/dev/null").toStdString();
 	_ofs.open( fileName.c_str() );