Tell fabric to get usernames from .ssh/config

arb33 has an issue whereby his laptop username is arb, but needs to ssh
in as arb33. Fabric, by default, does not look inside the SSH config
file so without this patch tries to login as arb.
Don't specify $USER when we SSH into DHCP. We should just use the default.
Merge branch 'no-ssh-hard-coded-username' of /srv/git/repositories/infrastructure/husky-scripts into upstream
Merge branch 'use_ssh_config' of /srv/git/repositories/infrastructure/husky-scripts into upstream
Merge branch 'upstream'
Update changelog for v0.0.20
Merge branch 'packaging'