introduced booking class with date
controller need to be updated, db test passes
Merge remote-tracking branch 'origin/master'

Conflicts:
	create_schema.sql
	model_hotelverwaltung.mwb
	src/gui/book/room/SelectCostumerByRoomFrameController.java
	src/gui/combinedbooking/SelectCostumerByRoomFrameController.java
	test/appTest/DBOperations.java