PEP8 cleanups.

mayan/apps/documents/views.py

@@ -8,7 +8,6 @@ from django.conf import settings
 from django.contrib import messages
 from django.core.exceptions import PermissionDenied
 from django.core.urlresolvers import resolve, reverse, reverse_lazy
-from django.template.defaultfilters import filesizeformat
 from django.http import HttpResponse, HttpResponseRedirect
 from django.shortcuts import render_to_response, get_object_or_404
 from django.template import RequestContext