Switch the file backend over to referencing tasks by label.

Also add an option to run over multiple files per job.
Fix file references that got broken through daemonizing.

We change lobster's working directory to the one specified in the config,
and thus all files referenced need either the old workind directory path or
the config directory path prepended.
Pull the dataset querying out of the SQL backend.
Add an option to run in the foreground to process tasks.

This will print error messages and logging output to stdout.