Cohorts may be uploaded via text file. The format of the file should be as follows:

* Each line of the file contains one record
* Each record is a series of data separated by commas (or other delimiters)
* The first record contains a list of fieldnames defining the format of the rest of the file
* Required fieldname is name
* Optional fieldnames are idnumber, description, descriptionformat, visible, context, category, category_id, category_idnumber, category_path
