Fix deprecation warnings for Django 1.11 and Django 2.0.

Signed-off-by: Roberto Rosario <roberto.rosario.gonzalez@gmail.com>

mayan/apps/document_comments/views.py

@@ -1,7 +1,7 @@
 from __future__ import absolute_import, unicode_literals
 
-from django.core.urlresolvers import reverse
 from django.shortcuts import get_object_or_404
+from django.urls import reverse
 from django.utils.translation import ugettext_lazy as _
 
 from acls.models import AccessControlList