Create app

Create django application providing annotator-storage functionality.

https://openedx.atlassian.net/browse/TNL-780
1) On create there is no 'created' or 'updated' field sent by annotatorjs so in this case it is possible to reject.
2) On update annotatorjs sends  'created' and 'updated' fields. edx-notes-api will filter this fields. In this case everything that comes from notes-api on retrieve will come on update back and it seems this is right behavior. 
Answering your question - yes this is explicit decision to filter `created` and `updated` fields and not HTTP 400 them.