Brawlstats

Fixed
- Brawler leaderboards for Python 3.5

Fixed
- Player model bug

Added
- An alias for `Player.x3vs3_victories` called `team_victories`

Added
- `reason` attribute for `NotFoundError`
Removed
- BrawlAPI client
Changed
- `Client.get_datetime` moved to utils
- `get_rankings` now requires all arguments to be keyword arguments
Fixed
- Brawler leaderboard now works

Changed
- Leaderboard functions reverted to one function for all types of leaderboards/rankings

Added
- `invalid_chars` attribute for `NotFoundError` when applicable
- `url` attribute for all errors that have requested a URL
- `str(error)` will return the message attribute of the error.
Changed
- The `error` attribute for all errors have been renamed to `message`
- For BrawlAPI: `get_leaderboard` split up into `get_player_leaderboard`, `get_club_leaderboard`, and `get_brawler_leaderboard`
- For the official API: `get_rankings` split up into `get_player_rankings`, `get_club_rankings`, and `get_brawler_rankings`