*/Vagrantfile: Select unique ssh port so builds can be simultaneous

Use auto_correct: true to allow for collisions to be nonfatal

Signed-off-by: Dan Mick <dan.mick@inktank.com>
urllib-bootstrap-salt.sh: as in calamari: use private version, save download

Signed-off-by: Dan Mick <dan.mick@inktank.com>
Merge branch 'wip-sshport' into wip-combined
Merge branch 'wip-salt-bootstrap' into wip-combined