authorized persons for a traveler

[dongliu]

The work represented by a traveler might need a list of persons each of whom authorized by an authorizer.

A traveler needs to have a authorizer list. A authorizer can add a person to the authorized persons list, and remove her/him from the list. The traveler owner add/remove an authorizer to the traveler.

A traveler needs to have an authorized persons list. An authorzied person has authorized by property.

The authorization may have an expiration date.