Use mark_safe to use html in users list admin

When setting api key, decode the generated key from bytes to str to avoid b'...' bit

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

Update docs to reflect new maximum timeout value

Based on this change:
166115ebfb

let there be colour

Added deterministic handling of sqlite database location

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.