Return quota, available, waiting, enrolled numbers

[Zachary Lo]

Return quota, available, waiting, enrolled numbers

[Dipsy Wong]

added in commit 9aa7a26

structure:

courses_dict.json [course_id][section_index]{
    quota:{
        total,
             public
             hold[
             department{
                 quota,
                 enrol,
                 avail
            }]},
  enrol,
  avail,
  wait
}