Installation environment "realism"

[dlorenc]

Right now our jobs run in standard Docker containers (python/node/ruby) specifically, as root users, in a k8s cluster. This is probably fairly accurate to many CI jobs. In #47, I switched this to more closely resemble a developer's laptop or dev environment, where the code is installed as a non-root user in a home directory.

We should probably think through which other scenarios we want to support here - I don't think we need to pick just one!