Adding members to database on startup is horribly and needlessly inefficient

[Brayzure]

To test initial functionality, the client attempts to add every single member it sees to the database all over again. Initially, the database handled conflicts by ignoring the provided data, which meant that performance was acceptable. However, now that conflicts are resolved by pushing the member's join date to the join_dates array, there is a very real performance hit (close to 3 minutes for 200k+ members), during which time the database is unusable. As soon as feasible, this needs to be resolved. Potentially need to pull all member and guild IDs, then check against that list before we ask the database to insert another row, or update an existing one.