This paves the way to hosting bitvend with NixOS.
Getting this to work required pulling in flask-oauthlib and a bunch of
older dependencies. This isn't great, but before we migrate
flask-spaceauth to use authlib that's what we have to do.
We also build pigpio/cygpio. pigpio should get upstreamed into nixpkgs.
We also rename bitvend.py to bitvend-run.py to unconfuse python paths.
To test:
nix build
result/bin/bitvend-run.py
informatic
q3k