Manual test: synthetic upgrade and rollback target with ostree commit

synthetic-upgrade-rollback

## Set up new branch based on existing tree and deploy
sudo ostree commit -b synthetic_test --tree=ref=fedora-atomic:fedora-atomic/24/x86_64/docker-host | tee target_commit.txt
sudo ostree admin deploy synthetic_test
sudo systemctl reboot
atomic host status
<active commit == target_commit.txt>

## Create a 'noop' commit based on the new branch as an upgrade target
sudo ostree commit -b synthetic_test --tree=ref=synthetic_test | tee target_upgrade.txt
sudo atomic host upgrade
sudo systemctl reboot
atomic host status
<active commit == target_upgrade.txt>

## Rollback to new branch
sudo atomic host rollback
sudo systemctl reboot
atomic host status
<active commit == target_commit.txt>

I'm rethinking the setup portion to create the new tree, deploy it, create the updated tree, then reboot

This seems to work the way we'll need it to in Tunir