Added helper functions, improved UI

InvenTree/InvenTree/models.py

@@ -90,6 +90,10 @@ class InvenTreeTree(models.Model):
 
         return unique
 
+    @property
+    def has_children(self):
+        return self.children.count() > 0
+
     @property
     def children(self):
         contents = ContentType.objects.get_for_model(type(self))