[SSF] Members for tasks

Added an "Interested" field that would show up in the rheader/form for Tasks, and users can 'Watch' a task(i.e, assign themselves a 'following' role). However, deployment settings can be changed to allow Users to assign themselves other roles such as "Mentor", "Volunteer" that shows up as a dropdown-list along with the "Watch" button.

So it should be:

    response = current.response
    s3 = response.s3
    s3db = current.s3db
    auth = current.auth

no?