Unregistered tab show shadow devices when replug same device

**Context**
The gateway is configured and the user wants to register a device.
**Expected Behavior**
When device is plugged on the power supply a card should be shown. And if the device is removed from the power supply the card should be removed after a while.
**Current Behavior**
The card is not removed.
**Possible Solution**
For each device that is scanned, there is a timeout associated to it. If on the next scan the device was not discovered the timeout should remove the card from the card list
**Steps to Reproduce**
1. Configure the gateway
2. Connect to the gateway
3. Plug a device on the power supply
4. The user should see the device on the unregistered tab
5. If you unplug and plug the device again the user should see the same device on the card list but with a different MAC address