src: add portNumbers property to Device

- Add new test.
- Update Readme.
test: fix test statement
Merge pull request #58 from santigimeno/get_port_numbers

Add portNumbers property to device
Remove OutEndpoint::startStream and related.

They don't work as they should, and no one uses them.
Rename stream -> poll

To better reflect what it does, and to avoid confusion with Node streams
and USB3 bulk streams, neither of which it is related to.
Use per-endpoint timeout settings.
Don't shadow read-only property for compatibility with strict mode