Fix deprecation warnings for Django 1.11 and Django 2.0.

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

mayan/apps/linking/views.py

@@ -3,8 +3,8 @@ from __future__ import absolute_import, unicode_literals
 import logging
 
 from django.contrib import messages
-from django.core.urlresolvers import reverse, reverse_lazy
 from django.shortcuts import get_object_or_404
+from django.urls import reverse, reverse_lazy
 from django.utils.translation import ugettext_lazy as _
 
 from acls.models import AccessControlList