fix pyflakes

shadowsocks/asyncdns.py

@@ -18,7 +18,6 @@
 from __future__ import absolute_import, division, print_function, \
     with_statement
 
-import time
 import os
 import socket
 import struct

shadowsocks/udprelay.py

@@ -62,7 +62,6 @@
 from __future__ import absolute_import, division, print_function, \
     with_statement
 
-import time
 import socket
 import logging
 import struct

tests/gen_multiple_passwd.py

@@ -1,6 +1,5 @@
 #!/usr/bin/python
 
-import os
 import json
 
 with open('server-multi-passwd-performance.json', 'wb') as f: