Will have to deal with when a player is no longer returned by fantasybaseballnerd, but is in use in peoples teams.
Some examples of when this would happen: a player retires, a player is demoted out of mlb.

Will have to deal with when a league owner deletes their account or league

what to do if any of the things are deleted that have a reference id in notification table

todo items (not a priority):
    player photos
    trading
    auto score keeping
    divisions (split league into different groups for places)

notifications that will exist:
    your turn to draft
    your player was injured
    someone wants to join your league
    someone invited you to join their league
    your player is inactive

automated processes:
    refreshing players and their stats, setting players inactive: notification
    populating injuries: notification