Fix more Django 2.0 deprecation warnings around URLconfs.

openedx/core/djangoapps/api_admin/api/urls.py

@@ -3,6 +3,7 @@ URL definitions for api access request API.
 """
 from django.conf.urls import include, url
 
+app_name = 'api_admin'
 urlpatterns = [
     url(r'^v1/', include('openedx.core.djangoapps.api_admin.api.v1.urls', namespace='v1')),
 ]

openedx/core/djangoapps/api_admin/api/v1/urls.py

@@ -5,6 +5,7 @@ from django.conf.urls import url
 
 from openedx.core.djangoapps.api_admin.api.v1 import views
 
+app_name = 'api_admin'
 urlpatterns = [
     url(r'^api_access_request/$', views.ApiAccessRequestView.as_view(), name='list_api_access_request'),
 ]

openedx/core/djangoapps/api_admin/urls.py

@@ -15,6 +15,7 @@ from openedx.core.djangoapps.api_admin.views import (
     CatalogSearchView
 )
 
+app_name = 'api_admin'
 urlpatterns = (
     url(
         r'^status/$',

openedx/core/djangoapps/catalog/urls.py

@@ -2,6 +2,7 @@ from django.conf.urls import url
 
 from . import views
 
+app_name = 'catalog'
 urlpatterns = [
     url(r'^management/cache_programs/$', views.cache_programs, name='cache_programs'),
 ]

openedx/core/djangoapps/credit/urls.py

@@ -22,6 +22,7 @@ router.register(r'courses', views.CreditCourseViewSet)
 router.register(r'providers', views.CreditProviderViewSet)
 V1_URLS += router.urls
 
+app_name = 'credit'
 urlpatterns = [
     url(r'^v1/', include(V1_URLS)),
 ]

openedx/core/djangoapps/dark_lang/urls.py

@@ -6,6 +6,7 @@ from django.conf.urls import url
 
 from openedx.core.djangoapps.dark_lang import views
 
+app_name = 'dark_lang'
 urlpatterns = [
     url(r'^$', views.PreviewLanguageFragmentView.as_view(), name='preview_lang'),
 ]

openedx/core/djangoapps/embargo/urls.py

@@ -4,6 +4,7 @@ from django.conf.urls import url
 
 from .views import CheckCourseAccessView, CourseAccessMessageView
 
+app_name = 'embargo'
 urlpatterns = [
     url(
         r'^blocked-message/(?P<access_point>enrollment|courseware)/(?P<message_key>.+)/$',