Initial commit of simple CI code

I have all the bits needed for a simplified distributed CI, but it doesn't yet run the tests. I have a few more hours work to get everything running as expected, but I thought I should check in some code by now.
I think you could use run_or_fail in these cases too, like so:

COMMIT=$(run_or_fail "Could not call 'git log' on repository" git log -n1)