This is a builder image intended to make it easy to build
images for projects that use pbr and bindep.
Also, build a python-base image for use with python-builder
pbrx installed dumb-init in a base image and used it as an
entrypoint for the image. This is a good pattern that we should
continue. Make a python-base image that can be used in the FROM
line of consuming final images.
Change-Id: I8da39e680e9c5ca0d8f603a2645e83fc3be87a8b
0e1cd6ee85