Corrected description of the parameters of the functions * _users_to_group
Corrected $ st->setCourse(->id) -> ->setCourse(->id)
Removed invalid method call error (from the class EnrolRecord) substituted by assigning the error string to -> error
Merge pull request #7 from MicaelRodrigues/master

Inconsistencies in the *_users_to_group functions and description