Initialise clients outside the app

This avoids the annoying problem where you can’t import a client unless
the app has already been initialised.

app/notify_client/status_api_client.py

@@ -8,3 +8,6 @@ class StatusApiClient(NotifyAdminAPIClient):
 
     def get_status(self, *params):
         return self.get(url='/_status', *params)
+
+
+status_api_client = StatusApiClient()