Days interval in 'Task Completation Lead/Lag' should be Integer

FEA: ItEr76S15OrganizingPerProjectDashboard

libreplan-webapp/src/main/java/org/libreplan/web/dashboard/DashboardModel.java

@@ -418,7 +418,8 @@ public class DashboardModel implements IDashboardModel {
 
         @Override
         public String toString() {
-            return String.format("[%.2f, %.2f]", min, max);
+            return String.format("[%d, %d]", (int) Math.ceil(min),
+                    (int) Math.ceil(max));
         }
 
     }