Allow 'assignees' on incidents

[benjaminxscott]

Build a method for people to 'propose themselves' as an assignee

• ability for creator to say "anyone can take it" or "I want to vet each potential person"
  • they choose a role, can be multiple
    with status
• i.e. capture who has taken action
  • captured in STIX as 'responder', etc depending on role

list show up on incident display

• Jim, Bob, and Jeffhave all said they want to respond
  Up to them to hash or