Added ability to define permission identifier
Added ability to define permission identifier

refs #9866

- by default it used `options.id`, which tells the permission layer the target id
- but some controllers want to use a different identifier
- e.g. settings -> settings.key
- e.g. password changes -> password[0].user_id

ErisDS/Ghost,e10/Ghost,ErisDS/Ghost,janvt/Ghost,ErisDS/Ghost,bitjson/Ghost,TryGhost/Ghost,Gargol/Ghost,JohnONolan/Ghost,TryGhost/Ghost,JohnONolan/Ghost,janvt/Ghost,kevinansfield/Ghost,kevinansfield/Ghost,TryGhost/Ghost,bitjson/Ghost,e10/Ghost,Gargol/Ghost,Kikobeats/Ghost,JohnONolan/Ghost,Kikobeats/Ghost,Kikobeats/Ghost,kevinansfield/Ghost