lazy property won't be maptoJSON ,and won't be correct de

swift 4
HandyJSON 4- beta1
```
lazy var status:Int = {
switch self.order_status {

case .toTake:
return 0
case .taken:
return 0
case .done:
return 1
}
}()
```
it won't be map to JSON
but if force set
```
let _ = taskList.req.status
```
it will be `status.storage=0`

Start by reproducing the lazy Swift property case described in the issue with HandyJSON 4-beta1, then inspect the mapping path used by mapToJSON and lazy properties. Done means the property is serialized with the correct value without first reading status, with a regression test covering both behaviors.

Written by the indexing model from the issue text.