Swarming bot runs run_isolated inside a docker container

[GoogleCodeExporter]

This is mostly to reduce the junk that can be left around. There's multiple 
non-trivial issues to fix, like where to fetch the containers from, how to 
define them and create them, how to reference them.

Obviously, this is linux specific so other solutions needs to be investigated 
for containment on other OSes

Original issue reported on code.google.com by maruel@chromium.org on 10 Feb 2015 at 8:18