* @param {object} obj params to pass to the api request
* @param {string} obj.id The url of the tournament to abortCheckIn
* @param {function} obj.callback A method to call when the API returns. Arguments are (error, data)
* @description
* When your tournament is in a 'checking_in' or 'checked_in' state, there's no way to edit the tournament's start time (start_at) or check-in duration (check_in_duration). You must first abort check-in, then you may edit those attributes.
* <pre>
Makes all participants active and clears their checked_in_at times.
Transitions the tournament state from 'checking_in' or 'checked_in' to 'pending'
</pre>
* See the {@link http://api.challonge.com/v1/documents/tournaments/abort_check_in|Challonge API Doc} for a full list of object properties.