I think this is a good suggestion and we can discuss it on our mailing list. There is much more changes that will be required sooner or later because database structure is not accepted yet and it still changes. 
There is no 'Tasks list' view or 'Add task' view implemented for now and tasks or their number were not the real part of functionalities included in this pull request. 
If you need this modification now, I can handle it till tomorrow's evening (with some methods automatically increasing the value of this attribute when adding a new task) but I am not sure if this issue should hold up the pull request from merging.