mehr tests mit Mocks
Interfaces vereinheitlichen
shouldChangeState bei ParkingSelectedState überschreiben
Merge branch 'master' into unittests

Conflicts:
	src/main/java/ch/zhaw/id5848/parkingmeter/core/ParkingMeterController.java
	src/main/java/ch/zhaw/id5848/parkingmeter/view/DisplayDevice.java
	src/test/java/ch/zhaw/id5848/parkingmeter/core/ParkingMeterControllerTest.java
new GUI interface, use dependency injection for constructor
Merge branch 'architecture'