This avoids duplicate calls to Check.get_grace_start() in several places.

when 10 or less remaining.

urlsafe_b64encode return a byte, which will result in an api key saved with something like b'apikey'
I did not tested it but urlsafe_b64decode looks like doing the job also.

sendreports: use select_related() to avoid doing N queries

When running the migration command from outside of the application directory the sqlite database is created in the current working directory at the time of the command being executed. This commit updates the file path to be relative to the location of the settings file.