Data Models finished
Changes:
- AvailabilityManager.java : this is the time manager.
- ParkingSpot.java: removed availabilityMap, added relationship for AvailabilityManager and added Image using ImageModel (from Randy). Note that Lat Lon is stored as GeoPoint object (brute force)
- User.java: added relationship for reviews, added details for contactInfo, licensePlate and role using enumeration.