Forest tests

src/main/java/controller/Controller.java

src/main/java/model/GameModel.java

src/main/java/model/city/CityStatistics.java

src/main/java/model/common/Constants.java

src/main/java/model/common/ZoneSatisfaction.java

src/main/java/model/facility/Forest.java

src/main/java/model/zone/IndustrialZone.java

src/main/java/model/zone/Zone.java

src/test/java/controller/ControllerTest.java

src/test/java/model/GameModelTest.java