Explicit is_teacher for group.
Explicit is_teacher for group.

cganas/picoCTF-web,picoCTF/picoCTF-web,cganas/picoCTF-web,cganas/picoCTF-web,picoCTF/picoCTF-web,picoCTF/picoCTF-web,picoCTF/picoCTF-web,cganas/picoCTF-web