Only enable notification ack button if there are any unread ones

src/views/notifications.js

@@ -9,6 +9,7 @@ angular.module('Application').controller('NotificationsController', ['$scope', '
     $scope.notifications = [];
     $scope.activeNotification = null;
     $scope.busy = true;
+    $scope.hasUnread = false;
     $scope.currentPage = 1;
     $scope.perPage = 20;
 
@@ -27,6 +28,7 @@ angular.module('Application').controller('NotificationsController', ['$scope', '
             });
 
             $scope.notifications = result;
+            $scope.hasUnread = !!result.find(function (n) { return !n.acknowledged; });
 
             $scope.busy = false;
         });
@@ -76,6 +78,7 @@ angular.module('Application').controller('NotificationsController', ['$scope', '
         }, function (error) {
             if (error) console.error(error);
 
+            $scope.hasUnread = false;
             $scope.clearAllBusy = false;
         });
     };