Convert chroot_setup to Python

[kadler]

This is a complicated enough that it should be written in a higher level language.

[markirish]

@abmusse are you trying to work on this? I have a local branch with most of it rewritten already, just needs testing for the various edge cases

[abmusse]

Yeah I was planning on working on this but have not started on it yet. If you already have most of it written already I can help test things out.