Also moves port mappings out of the SQL DB and into a file on
disk. These could get very sizable (hundred to thousands of
ports) so moving them out to a file will keep the DB small and
fast.
Finally, add a foreign key reference from container ID to
container state ID. This ensures we never get into an
inconsistent state where we have data in one table but not the
other.
Signed-off-by: Matthew Heon <matthew.heon@gmail.com>
Closes: #225
Approved by: baude