The Dockerfile did not work as is, because the dependencies in
requirements.txt are newer than the stretch-image with its python v3.5
can support/run. Use stable debian with the lts nodejs instead, plus
had to add some libs to make the wheel build succeed.
jsonschema v4 breaks things, so its version needs to be pinned until
bravado is fixed [0].
[0] https://github.com/Yelp/bravado-core/pull/385/files#r731674447
