[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.

I /had/ to use a Custom Method here, couldn't find( maybe I'm not aware of it ?) any such already existing functionality to do what I was planning to do. What I want to do is be able to insert data in a table whose form doesn't exist in the UI....because I don't need the form as I already know the data to insert( i.e, the task opened and the user logged in ), however CRUD operations end up in SQLFORM at the very low level. So I had to make the Method to handle Ajax to accept the data to insert, update or delete it. Any hints to a similar feature already implemented in some form or the other would be helpful ;)