Django 2.0 replaced django.core.urlresolvers with django.urls

[sona-karakhanyan]

django-seo2 is broken

from django.core.urlresolvers import (RegexURLResolver, RegexURLPattern, ModuleNotFoundError: No module named 'django.core.urlresolvers'

Refer to "django.core.urlresolvers" entry on their deprecation doc.

[mahdiabdollahpour]

Django 2.0 removes the 'django.core.urlresolvers' module, which was moved to 'django.urls'

django seo must become django2 comaptible