Rails todo with contacts

The penultimate commit works and uses a dropdown menu. The menu displays a blank plus each contacts name. If the blank is chosen, no one will be added. If a person already on the task is chosen, no one will be added. If a person NOT assigned to the task is chosen, he/she will be added. People cannot be removed from tasks.

In the final commit I tried to implement Phil's suggestion of replacing the dropdown menu with checkboxes. This works somewhat, but you can only add one person at a time it seems, and you can only add people with an id number higher than everyone else already on the task. Also, you cannot remove people from the task by unchecking them. 

The dropdown menu works fine, but the code is kind of bulky and inelegant. Might try and investigate the checkbox idea further if time allows. Good night!