Handle there not being a webhook set up

handler/revolut.py

@@ -128,6 +128,8 @@ class Revolut(object):
         if r.status_code == 200:
             parsed = r.json()
             return parsed
+        elif r.status_code == 404:
+            return {}
         else:
             self.log.error("Cannot get webhooks: {content}", r.content)
             return False