[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/web/login.py

@@ -1,10 +1,10 @@
-#import sqlite3
-from flask import (Blueprint, flash, g, redirect,
-                   render_template, request, session, url_for)
 import functools
-from setting import Config
 import hashlib
 
+from core.config_manager import Config
+from flask import (Blueprint, flash, g, redirect, render_template, request,
+                   session, url_for)
+
 bp = Blueprint('login', __name__, url_prefix='/web')