User able to
1. login with username+password
2. Create 1/more campaigns
3. Upload pictures to a campaign
4. Create ad from available images & assign to specific ad slot as specified in table
5. Pause/Stop campaigns
6. Assign loaded credit to a specific campaign budget
7. Alter a campaign budget
8. Access a console displaying all ongoing campaigns and the remaining credit/budget
9. Download summary report

Admin:
Everything in users except alter/load-budget.
Approve/Deny uploaded images and campaigns
Create/Update/Delete ad slots & properties

Ad slot:
costs assigned (a field for the cost per week and cost per day)
default image when unoccupied
hierarchical & can have parent-child relationships e.g Tech>Android>Samsung