change loading screen.
Added loading image within loading porting in Application.
Implemeted loading functionality in all the navigation menu
Updated UI for Assessment.
Merge remote-tracking branch 'origin/loading_screen'

Conflicts:
	bme2/src/main/java/medizin/client/activites/ActivityQuestionDetails.java
	bme2/src/main/java/medizin/client/activites/ActivityQuestionEdit.java
	bme2/src/main/java/medizin/client/activites/ActivityQuestionInAssessmentDetails.java
	bme2/src/main/java/medizin/client/ui/view/QuestiontypesEditView.java
	bme2/src/main/java/medizin/client/ui/view/QuestiontypesEditViewImpl.java