First draft of aupdate-proxy-dns playbook.
Include update-proxy-dns in vhost_reboot.yml.
Use a real tmpdir.
atomic: Update our config.py to the latest fedmsg-atomic-composer upstream
atomic: Use the masher user instead of rpmostreecompose

We need this because we'll be composing trees as the bodhi user
atomic: Pull the latest package from the main infra repo