Test and container env are too tightly coupled

The tests are too tightly coupled to the environment provided by the "micro-osd.sh" script. It currently hard-codes some names, and assumes some other things.
We should avoid hard coding as much as possible and pass expected configuration into both the setup script, to set up ceph server components that the tests needs, and then to the tests themselves.

To start simple we could just pass these to both programs as a set of environment variables.