Refactored TestCustomerImpl and renamed it. Then fixed some faulty Date
objects. January is MONTH 0!
Fixed Nullpointer in TestFindHOtelStayForCustomer.
Rewrote timeOverlap() method, logic is now correct. Fixed
TestHotelStayImpl which tests this.
Merge branch 'dev' of ssh://git@github.com/ModelDrivenMiddleEarth/ModelDrivenHotel.git into dev