Serialization fixes

[mfojtik]

• First patch revert new k8s JSON encoder to standard Go library encoder until we figure out why it fails to decode "\"" in DockerImage
• Second patch wraps the legacy and grouped scheme in order for both to have conversion functions

[mfojtik]

@deads2k the second patch requires sanity check

[deads2k]

removing jsoniter is fine. I'd like you remove all traces in a single commit and we'll try to figure out the problem later.

@liggitt as predicted...

[liggitt]

@mfojtik don't forget openshift#16065

[liggitt]

I'd prefer commenting out all references to jsoniter in the file so the import is dropped... too easy for new references to creep in without conflicts on a rebase

[mfojtik]

@deads2k is this acceptable? drop in/out and the serialization test is passing with this.

[mfojtik]

@liggitt do you want to drop it entirely from k8s? remove all references, get rid of vendor/ ?

[mfojtik]

@liggitt i think the only place where it is used right know that matters is the json serializer. There are some occurrences in _tests but nothing that we run I assume.

[mfojtik]

updated... I comment it out instead of removing and commented the initialisation so we don't import it anymore.