remove unnecessary imports

isso/db/comments.py

@@ -2,7 +2,6 @@
 
 import time
 
-from isso.db import spam
 from isso.utils import Bloomfilter
 from isso.compat import buffer
 

isso/db/spam.py

@@ -1,7 +1,6 @@
 # -*- encoding: utf-8 -*-
 
 import time
-import functools
 
 
 class Guard:

isso/views/comments.py

@@ -15,7 +15,7 @@ from werkzeug.exceptions import BadRequest, Forbidden, NotFound
 
 from isso.compat import text_type as str
 
-from isso import utils, local, db
+from isso import utils, local
 from isso.utils import http, parse, markdown
 from isso.utils.crypto import pbkdf2
 from isso.views import requires