fix KaaSerde definition (#52)

review class names (#50)

move onerror inside start function (#46)

Feature/start schemaregistry ondemand (#43)

- Rename `GenericSerde` to `KaaSerde` (to support case classes serialization/deserialization)
- Add `KaaGenericSerde` to support serialization/deserialization of `GenericRecord`.
- Add `KaaSerde` and `KaaGenericSerde` implicits (close #42)
- `KaaSchemaRegistry.start` should be called to connect to Kafka and start consuming records (instead of automatically connect in constructor). This is to have a more controller life cycle, for example creating the instance but do not connect yet (useful for DI). And now you can `close` and `start` multiple times reusing the same instance. (close #36)

rename packages

stop producer on close (#35)

handle null in genericserde for kafka tombstones handling (#34)

java compatibility fix (#33)

add props inside admin and refactoring (#32)

allow to use kafka properties (#31)

* allow to use kafka properties