Cleanup socket handling:
* Use new duppy `Accept API
* Remove open Unix from server and harbor for clarity
* Implement wait_for using Duppy. This should allow for
  more atomic mutex action and also cleaner select handling
  with read and write tests.
Simplify a bit.
Scrap previous implementation and use select.
Also leave original exception here, we have printers for that now
and that keeps stack trace around..
Merge pull request #50 from savonet/socket-cleanup

Cleanup socket handling: