Fixed model & layer download / upload

mozen/src/main/java/mozen/business/IUserManager.java

mozen/src/main/java/mozen/business/LayerManager.java

mozen/src/main/java/mozen/business/ModelManager.java

mozen/src/main/java/mozen/business/UserManager.java

mozen/src/main/java/mozen/model/CustomLayer.java

mozen/src/main/java/mozen/model/Model.java

mozen/src/main/java/mozen/web/CustomLayerController.java

mozen/src/main/java/mozen/web/ModelController.java

mozen/src/main/resources/application.properties