readOnly properties are not initializable

[fatadel]

node-wot approach:

1. Create a readOnly property.
2. Make it changeable from the creator Thing but keep it read-only for all the clients.
3. Initialize it with thing.writeProperty.

---

wot-py approach:

1. Create a readOnly property.
2. And now the property is read-only for everyone, even the creator Thing, which makes it not initializable as well.