fixed some of the schema

Did most of Atsu's requests except still need to:
-"Most of these should have "not null" constraints"
-"represent the completed status with just a single completed_time field that's allowed to be null"
-"arrays in db"
Maybe a better name for these 2 would be something like "delivered_at" and "picked_up_at" to follow the convention of the autoadded datetime fields?