Remove usage of url.patterns as per Django's deprecation warnings.

mayan/apps/document_comments/urls.py

@@ -1,14 +1,13 @@
 from __future__ import unicode_literals
 
-from django.conf.urls import patterns, url
+from django.conf.urls import url
 
 from .views import (
     DocumentCommentCreateView, DocumentCommentDeleteView,
     DocumentCommentListView
 )
 
-urlpatterns = patterns(
-    '',
+urlpatterns = [
     url(
         r'^comment/(?P<pk>\d+)/delete/$', DocumentCommentDeleteView.as_view(),
         name='comment_delete'
@@ -21,4 +20,4 @@ urlpatterns = patterns(
         r'^(?P<pk>\d+)/comment/list/$',
         DocumentCommentListView.as_view(), name='comments_for_document'
     ),
-)
+]