the `os_version` is defaulting to the `image_tag` inside containers and
causing our template to use latest tag
---------
Co-authored-by: Gerald Pinder <gmpinder@gmail.com>
Since the command `ostree container commit` checks for the presence of
mounted directories, we will be running it at the end of each module
run. We have also updated the final commit to remove from /tmp/ and
/var/ again in case a user creates extra files through custom
instructions.
Closes#101#95
