Return all day off recorded for given month and person.
GET
/data/persons/{person_id}/day-offs/month/{year}/{month}
curl \
-X GET http://api.example.com/data/persons/{person_id}/day-offs/month/{year}/{month}
curl \
-X GET http://api.example.com/data/persons/{person_id}/day-offs/month/{year}/{month}