Update Carnegie Mellon LDAP integration (#1422)
Update Carnegie Mellon LDAP integration (#1422)

- Stop using the legacy LDAP server
- Check for the currently used value denoting first year students
cg2v/Autolab,cg2v/Autolab,cg2v/Autolab,autolab/Autolab,autolab/Autolab,autolab/Autolab,cg2v/Autolab,autolab/Autolab,autolab/Autolab,cg2v/Autolab,cg2v/Autolab,autolab/Autolab