Sindbad~EG File Manager

This files describes API changes in /cohort/ information provided here is intended
especially for developers.

=== 3.1 ===
* The Webservice core_cohort_get_cohorts now has the added functionality of getting all cohorts
  by not passing any parameters

=== 2.6 ===
* Webservice core_cohort_update_cohorts was incorrectly specifiying float as the parameter type
  for cohort id. This field is actually int and input is now reported and processed as such.
* Webservice core_cohort_get_cohorts was incorrectly specifiying float as the return
  type for cohort id. The actual return type is int and is now reported as such.