Fix for #274.

[neopholus]

Now it is tracked whether a device comes from the configuration or from the auto discovery:

• Devices from the configuration are created using the name from the configuration as it was done before 3.0.3 introduced MAC addresses as names for devices that has been auto-discovered. Unfortunately, devices added to the device tab of the configuration broke with that, as also there MAC addresses would have been used as name and not the configured name. For devices in different subnets, the getMAC failed, of course.
• Devices from the auto discovery are using MAC address as name, as introduced with 3.0.3.