Drop old Python and Django versions (#220)

* drop old python and django versions

* fix tests

* remove compat module entirely

Co-authored-by: Fabio Caccamo <fabio.caccamo@gmail.com>

admin_interface/static/admin/js/popup_response.js

@@ -42,11 +42,7 @@
             if (typeof(openerRef.dismissAddRelatedObjectPopup) === 'function') {
                 openerRef.dismissAddRelatedObjectPopup(windowRef, initData.value, initData.obj);
             }
-            else if (typeof(openerRef.dismissAddAnotherPopup) === 'function') {
-                // django 1.7 compatibility
-                openerRef.dismissAddAnotherPopup(windowRef, initData.value, initData.obj);
-            }
             break;
     }
 
-})();
+})();