Fix some flake8 lint error.

fabfile.py

@@ -1,7 +1,6 @@
 # coding: utf-8
 
-import os
-from fabric.api import env, local, cd, run, sudo
+from fabric.api import env, local, cd, run
 from fabric.operations import put
 
 env.user = 'www'

june/htmlcompress.py

@@ -11,7 +11,7 @@
 """
 import re
 from jinja2.ext import Extension
-from jinja2.lexer import Token, describe_token
+from jinja2.lexer import Token
 from jinja2 import TemplateSyntaxError
 
 

june/tasks/mail.py

@@ -1,6 +1,5 @@
 # coding: utf-8
 
-from flask import Flask
 from flask import current_app, url_for, render_template
 from flask.ext.babel import gettext as _
 from flask_mail import Message

manager.py

@@ -6,8 +6,7 @@
 
 import os
 import sys
-import argparse
-from flask_script import Manager, Command
+from flask_script import Manager
 from june.app import create_app