Update packages in docker image; supress pip warning; improve cache use apk to update packages in image to get security fixes pip warns when run as root. In a dcker environment this can be ignored as the entire image is effectively a venv. Move inclusion of specific pip packages lower in the build procedure so we can cache all prior layers. Including it earlier resulted in layers that could be cached being invalidated.

#!/usr/bin/env python
from __future__ import print_function
import zlib, base64, sys
print(base64.encodestring(zlib.compress(sys.stdin.read())))