user now has last coupon left at location presented to them (for now just as an alert, but ventually stored into their account)
at this point, the full functionality of locations and coupons has been implemented. users can choose a coupon to leave, it is left at only one location, and the most recent coupon left at that location is delivered to the user in the form of an alert. left to do: implement different users signing in, and having their coupons listed. going to first clean up the code
done