[serialization] Add initial serialiser for JSON
[meta] Add type of the attribute
[example] Inspect type of attribute
[example] Update model
[core] Allow to cast identifier to the desired type
[serializer] Add JSON entity serializer
[data] Use typed value of identifier
[example] Allow to make GET request on real data
Merge branch 'json-serializer'
[data] Return 404 if entity with identifier was not found