make sure response is returned for add_to_workspace calls (#375)

nanome/beta/nanome_sdk/session/session_client.py

@@ -120,7 +120,9 @@ async def add_to_workspace(self, complex_list):
         message_type = Messages.add_to_workspace
         expects_response = True
         args = complex_list
-        self._send_message(message_type, args, expects_response)
+        request_id = self._send_message(message_type, args, expects_response)
+        result = await self._process_payload(request_id)
+        return result
 
     async def remove_from_workspace(self, complex_list):
         """By removing all atoms from complexes, we can remove them from the workspace."""