PEP8 cleanups.

mayan/apps/common/forms.py

@@ -6,7 +6,6 @@ from django import forms
 from django.conf import settings
 from django.contrib.auth import get_user_model
 from django.db import models
-from django.utils.html import escape
 from django.utils.translation import ugettext_lazy as _
 
 from .classes import Filter, Package