To-do completed notifications should only be sent to person who created the to-do, not everyone who was assigned the to-do Merged

Currently, if you assign a to-do to multiple people, when anyone completes the to-do both the creator and the all assignees on the to-do are notified.

This doesn't seem like it should work that way.

It's not my to-do, I was just one of the assignees on it. Also, I don't want to or need to be notified about other assignees completing this to-do. It is somewhat confusing actually because I have to determine if this was actually my to-do that I did assign or just noise from people completing to-dos that I was also assigned.