This creates more intermediates, but moves those that are less likely
to change to the top of the file. In theory this will produce faster
builds on a developer's machine as they won't need to apt-get update
every time.
This builds a working docker image for the application.
This is only an initial revision. It needs testing. MySQL, PIL, etc.
Was going to use Alpine, however, python3.6 segfaulted on docker
starting up, and I couldn't find the core files...
