Update to jackson 3.x

[krzyk]

Jackson 3.x introduced new packages, and quite a lot of other changes (https://github.com/FasterXML/jackson/wiki/Jackson-Release-3.0) it would be good to update to that version.

[krzyk]

I could give it a shot and submit PR.

I assume it would be best to have jackson3 module, so people could still use the old one.

[danjee]

The package names are different so imo it won't be a breaking change to have a new Jackson3Encoder/Decoder