Json serializing/deserializing of RIFAMessage

[nsforth]

Clustered EventBus in Vert.x requires redesign of VxRifa event bus codec. Codec should serialize somehow any objects to Json, String or Buffer. It's not so hard, but proper deserializing is. Possible solution: methods parameters in @VxRifa interfaces must have some kind of @JsonCreator, if parameter type has it, it should be possible to deserialize it from Json object. Cluster compatible interfaces will require @JsonCreator constructors for parameters. May be additional annotation @VxRifaDeserializer on methods parameters may solve problem. It will accept JsonDeserializer as an argument.