Make it clear that client do not use __init__

The clients never get passed useful values to their `__init__` methods.
Rather the real values are passed through later using the `init_app`
method.

So it should be an error if the client is relying on the values that
get passed to it’s init method. Easiest way to ensure this is by making
the `__init__` method not expect any arguments and passing fake values
to the `Super` call.

app/notify_client/api_key_api_client.py

@@ -9,10 +9,8 @@ KEY_TYPE_TEST = 'test'
 
 
 class ApiKeyApiClient(BaseAPIClient):
-    def __init__(self, base_url=None, service_id=None, api_key=None):
-        super(self.__class__, self).__init__(base_url=base_url or 'base_url',
-                                             service_id=service_id or 'service_id',
-                                             api_key=api_key or 'api_key')
+    def __init__(self):
+        super(self.__class__, self).__init__("a", "b", "c")
 
     def init_app(self, app):
         self.base_url = app.config['API_HOST_NAME']