PEP8 cleanups.

mayan/apps/metadata/views.py

@@ -4,7 +4,7 @@ from django.conf import settings
 from django.contrib import messages
 from django.core.exceptions import PermissionDenied
 from django.core.urlresolvers import reverse, reverse_lazy
-from django.http import HttpResponseRedirect, Http404
+from django.http import HttpResponseRedirect
 from django.shortcuts import get_object_or_404, render_to_response
 from django.template import RequestContext
 from django.utils.http import urlencode