Fetch all the information needed for 2.6 fullname()

Since 2.6, there are more mandatory fields to be
passed to fullname(). This implementation does it
conditionally, so the plugin will continue working
in older versions without problem.
Merge pull request #2 from stronk7/get_all_user_name_fields

Fetch all the information needed for 2.6 fullname()
V 1.3.0. Added: Course user list conditioned by group if course has group mode and logginer cannot access all groups.