Support for json-schema references

[wszydlak]

Changes:

• added support for json-schema $ref keyword - schema is automaticaly dereferenced by json-schema-ref-parser when schema file is loaded

[dmartinezg]

Apologies for not seeing this earlier.

Can you please add tests for this?

[alvassin]

Hmmm.. did not work for me for schemas, imported using schemas keyword in the beginning of the file.

[dmartinezg]

Hi @wszydlak, is this closed with the bigger version done by @alvassin? thanks for the work 👍