521 streamer updates are broken

Fixes #521 

Edit/update:
During the event propagation the action was decided by using a match on  ```flask.request.endpoint``` and the result can be either: 'create', **'update'** and 'delete'. However the streaming system were expecting either: 'create', **'edit'** and 'delete'. So it didn't do anything with an 'update' action.  Now it expects and uses 'update'. 

Delete:
Our ```after_request``` function in api/store.py dropped away all 'delete' actions, because the response here was empty and the ```annotation = json.loads(response.data)``` line would fail to it.
It has been extended, that for a delete action it uses flash.request.data as a source and it can propagate the delete action correctly.