Support for GUDE Expert PDU 3811 - 3810-Model already supported

Dear Observium-Devs,

recently we purchased metered PDUs from the German vendor GUDE. It turned out that the older Model 8310 is supported by Observium, so we tried to purchase the newer Model 8311 and hoped, that it is supported as well. First recognized as "Generic Device" we tried to add the sysObjectID to includes/definitions/os.inc.php as we are used to. It gets detected as GUDE Expert PDU, but the Sensors are missing. From the PDU we can download a MIB File, which i include here as well.

It would be nice to see the direct successor of the 8310 PDU working in Observium just as nice as the old model did.

Best regards from Austria,
Fabian