Allow adding packages to debootstrap

Also allows setting the "distro name" so that things that change the
debootstrap signature will have a different tarball.

This is being done in advance of a debian-upstart element to allow
experimenting with debian and upstart.

Change-Id: I1a558fdaf5924c65f1cced9f9bf29d73643c30af
Fix mysql package mappings for opensuse

Change-Id: I231df61a79e6c8686afbbd203fa6bba96497f228
Merge "Allow adding packages to debootstrap"
Merge "Fix mysql package mappings for opensuse"