Delete a Task

As an user, I can delete a task in order clean my history

Given the app is running
and, the current tasks are :

Name	Due date
This is my task tomorrow	12/11/2011
This is my second task for tomorrow	12/11/2011

When we delete the task named : This is my task tomorrow
Then the tasks should be

Is Done ?	Name	Due date
False	This is my second task for tomorrow This is my task tomorrow	12/11/2011 00:00:00
False	This is my second task for tomorrow	12/11/2011 00:00:00