[Enhance][Bug fix] Improve setting file & ...

- Fix a small bug that `best30` of API cannot have scores whose songs are not in database
- At present the setting file can be a module or a file with some of options
- Limiter can have multiple rules together now

latest version/server/__init__.py

@@ -1,5 +1,5 @@
+from core.config_manager import Config
 from flask import Blueprint
-from setting import Config
 
 from . import (auth, course, friend, multiplayer, others, present, purchase,
                score, user, world)