alter check for candidate_fits directory existence

[tylerbarna]

Currently, the make_jobs script will check if there is a directory in candidate_fits that corresponds to the new candidates daily folder. If it exists, the make_jobs.py script will exit. This behaviour prevents make_jobs from overwriting fits that are still being run, but I think we need to have a more robust method so we can run the script on existing objects for new models.

One option would be to create a .fitting file for each model that would be deleted upon completion or timeout to be replaced with the current .fin file. Then we could check if a .fitting or .fin file exists and exit if they are present. We could also probably make the check for candidate fits specific to each object and each model. Essentially, right now, as long as the script has been run on one object for one model, the script won't execute again, which is probably not the best option.

Issues with Piro2021 come to mind