expand on `remote_devices.yaml`

remote_devices.yaml currently represents a dict with device names as keys and the udp address as values:

camera: udp://[IP]:[PORT]

There are a few issues with this approach:

The current layout does not allow adding further properties in the future. It might make sense to nest the dict:
```
unique identifier:
  name: camera
  address: udp://[IP]:[PORT]
  property1: xyz
  property2: xyz
```
Using the name as an identifiers is prone to collisions (if, say, there are two computers identifying as camera). It might make sense to go with the device's unique MAC address?
```
58:11:22:b1:62:a5:
  name: camera
  address: udp://[IP]:[PORT]
```
The MAC address can be obtained like so:
```
key = ':'.join(re.findall('..', '%012x' % uuid.getnode()))
```
This way, machines could update their entries even in the face of dynamic IP addresses.
A date-field indicating the respective devices last announcement could be useful for cleaning up the list of devices

int-brain-lab / iblrig