Add support json-schema-draft-04

[vlcinsky]

json-schema-draft-04 would be great.

[themihai]

+1 ?

[shuc]

happy holidays :) any update for this issue ?

[goinnn]

+1

[vine77]

:+1:

[ebdrup]

I've compiled a list of the official draft-4 tests that are failing for JSV here https://github.com/Muscula/json-schema-benchmark/blob/master/reports/JSV.md

If you want draft-4 support perhaps take a look here for an alternative: https://github.com/Muscula/json-schema-benchmark