Avoid confirm close warning when you get a concurrent modification exception

When users clicks on save and the project has been already modified by other
user, it should be redirected to the page explaining the issue without having to
confirm that he is leaving the planning.

FEA: ItEr77S04BugFixing

libreplan-webapp/src/main/java/org/libreplan/web/common/concurrentdetection/ConcurrentModificationController.java

@@ -25,6 +25,7 @@ import javax.servlet.http.HttpServletRequest;
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
+import org.libreplan.web.common.ConfirmCloseUtil;
 import org.springframework.dao.OptimisticLockingFailureException;
 import org.zkoss.zk.ui.Component;
 import org.zkoss.zk.ui.Executions;
@@ -49,6 +50,7 @@ public class ConcurrentModificationController extends GenericForwardComposer {
                         "an OptimistLockingFailureException caused a disruption to an user",
                         exception);
         if (Executions.getCurrent() != null) {
+            ConfirmCloseUtil.resetConfirmClose();
             Executions.sendRedirect("/common/concurrent_modification.zul?back="
                     + backURL);
         } else {