Allow providing custom mount points to docker-compose template

[AlanCoding]

ISSUE TYPE

• Feature Idea

SUMMARY

Say that someone wants to do an in-place install of a python package on their computer while running docker-compose. They can do this if it's a sub-directory of the awx checkout, but not other places.

We should have some custom setting that will append to the docker-compose.yml template to add volume mounts for the control and execution plane nodes.