David can assign himself to a task

[chaojaim]

David can view the Tasks of a Project Tasks with no assigned user have an "Assign" link David can select the link and the Task user is updated with his user id David's name is now associated with Task

[chaojaim]

GIVEN David is on the Project view page AND he sees a list of Tasks THEN he sees a ‘Pickup Task’ button next to each Task where user_id is nil AND WHEN he clicks a button next to a Task THEN he is the Task updates with his User as owner THEN he is redirected back to the project view page AND he sees his name next to the Task