[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

.gitignore

@@ -1,5 +1,19 @@
+# log files
 *.log
+
+# SSL cert
+*.pem
+*.key
+
+# sqlite3 database
+*.db
+*.db.bak*
+
 # Byte-compiled / optimized / DLL files
 __pycache__/
 *.py[cod]
-*$py.class
+*$py.class
+
+# setting/config files
+latest version/config/
+latest version/config.py