Remove optionals on accessing GraphJSON properties

[Orkhan Alikhanov]

let json = GraphJSON(...)
guard let firstName = json.user?.name?.first?.asString else {
  return
}

Above can be reduced to:

guard let firstName = json.user.name.first.asString else {
  return 
}

We can continue to use asX anyways which returns Optional

[Daniel Jonathan]

Fixed in #146