isAdmin(person) determines if the specified user has
      Administrator authority.
  
    Parameters
- person
- A node representing the user to check.
Returns
Returns true if the specified user is an Administrator authority.
Example
var userName = "abeecher";
var user = people.getPerson(userName);
if(user){
    model.isAdmin = people.isAdmin(user);
    model.userName = userName;
}
    