[Bug #1146] Fixed model setting hasChangeLabels to true after a label remove

* Done for Hours worked per resource report

FEA: ItEr75S04BugFixing

navalplanner-webapp/src/main/java/org/navalplanner/web/reports/HoursWorkedPerWorkerModel.java

@@ -159,6 +159,7 @@ public class HoursWorkedPerWorkerModel implements IHoursWorkedPerWorkerModel {
     @Override
     public void removeSelectedLabel(Label label) {
         this.selectedLabels.remove(label);
+        hasChangeLabels = true;
     }
 
     @Override