Fix issue with add_column

Hopefully this would work now if someone needed to revert!
Changed model for dates

Request a date by using (Student object).update_attribute(:date_id, (other Student object).id)
Use .date_requested.all to see who has requested a date with a person
Use .date_requestor to see who a person has requested a date with
If a.date_id == b.id and b.id == a.date_id, it's mutual! Yay for a and b!!