For issue: #63

This PR adds the concept of 'modes'.
The existing method of creating the database will be determined by using the --default-mode commandline flag.

The new 'mode' that is introduced is updating the current season. This is specified by the --current_season_mode commandline switch. These are mutually exclusive groups in Gooey. This takes an existing database, loads all player_game_log entries into a temp table, then uses this new temp table (which should have more games than the existing player_game_log table) then uses set logic through an EXCEPT query to determine which games are new. This is used to update tables like game, shot_chart_detail, and player_game_log.

TODOs:

• If no new games are added, bail early.
  • Do this by evaluating the EXCEPT predicate early.
• Temp table creation atm conflicts with creating a fresh DB. The dependent objects do not yet exist.
  • Could be fixed by checking the current mode, if it was stored in the settings object.
  • Confirm that this is still broken after other changes before implementing.
• Expand what is stored in the Settings class.
  • We're passing alot of cmd line args to the different mode functions.
  • If they were stored in Settings it'd be easier.
• Move schema create function to db_utils.
• Evaluate temp table indexes
  • Most probably aren't needed?
• Figure out debug logging flags.
  • Would be useful to diagnose bugs by looking at the peewee queries.