making input optional for Conversation

Author: jsstylos

watson_developer_cloud/conversation_v1.py

@@ -29,7 +29,7 @@ def __init__(self, version, url=default_url, **kwargs):
         WatsonDeveloperCloudService.__init__(self, 'conversation', url, **kwargs)
         self.version = version
 
-    def message(self, workspace_id, message_input, context=None):
+    def message(self, workspace_id, message_input=None, context=None):
         """
         Retrieves information about a specific classifier.
         :param workspace_id: The workspace to use