Fix docker configuration

[visigoth]

These changes update the docker configuration to build correctly via
docker-compose. The prior configuration did not appropriately lock the
versions of various dependencies correctly and fail to work against the latest
versions of many of these packages. Therefore, the following changes were made:

• Build on top of CentOS7, which has the correct epel-release package available
• Use the python2 package as python is no longer available
• Lock the stack version to one that is compatible with the specified version of
  Cabal
• Use mongodb 4.0 because later versions lock down external access to
  system.indexes
• Ensure setools is built properly; it requires python setup.py build_ext
  prior to install
• Copy the V3SPA repository rather than clone from github. This is perhaps a
  controversial change, but i think better captures the intent of the docker
  build
• Use deltarpm for faster install
• Separate some commands to make it easier to debug intermediate builds