Feature/reduce payload size

* Limit the list of items fetched to 0, to reduce the payload
* Add a new call to check if the user has done the activity to set the proper status

This requires feature/MIE-1564.
Since they are always called together, what do you think about putting `@fetchActivityForUser()` inside of the snippet's `fetch` method that way you don't have to add independent calls for this method?