Naive implementation of client uniqueness validation
Naive implementation of client uniqueness validation

- validates for uniqueness on client
- does not handle asynchronous ops right

peterkacinec/engine,sosik/registries,peterkacinec/registries,MaxKarel/engine,MaxKarel/engine,peterkacinec/engine,tomatell/engine,peterkacinec/engine,tomatell/engine,peterkacinec/registries,sosik/registries,sosik/registries,tomatell/engine,peterkacinec/registries,MaxKarel/engine