initial implementation of reverse proxy, using django-revproxy from within a middleware

add new config entry "primary_domain" which is used to set the cookie domain

passbook/app_gw/apps.py

@@ -0,0 +1,11 @@
+"""passbook Application Security Gateway app"""
+from django.apps import AppConfig
+
+
+class PassbookApplicationApplicationGatewayConfig(AppConfig):
+    """passbook app_gw app"""
+
+    name = 'passbook.app_gw'
+    label = 'passbook_app_gw'
+    verbose_name = 'passbook Application Security Gateway'
+    mountpoint = 'app_gw/'