Remove Port class

Ultimately unnecessary with Cylon, as opposed to Artoo where we do some
interesting/tricky stuff with Socket-To-Serial to make everything work.

Minor changes need to be made to the following adaptors to make sure nothing breaks, which I'll do once this gets merged:

- `cylon-ardrone`
- `cylon-crazyflie`
- `cylon-firmata`
- `cylon-force`
- `cylon-rapiro`
- `cylon-sphero`
- `cylon-tessel`

:anchor: