Update JSON schema

[aeidi89]

Update the current 0.7 JSON schema to 0.9 JSON schema.

[UlrikeS91]

To do so, the validator has to be updated along with the actual change. @lzehl and I talked about this and thought it would be nice to update the validator to a more general one that can check against different drafts dependent on the draft used within schemas with "$schema": "http://json-schema.org/draft-XY/schema#". --> If XY is 07, check against Draft7Validator. If XY is 09, check against Draft9Validator.

@skoehnen, could you create such a validator?

[UlrikeS91]

@skoehnen and @lzehl, I don''t know the status of this. @xgui3783 has performed some fixes related to this issue, but is it fixed?

[lzehl]

@skoehnen OR @olinux : is the generator in the main openMINDS repo now using draft-07 or draft-09? or can you even choose between the json-schema draft (not sure if our schemas would actually look different...)?

[skoehnen]

I am still validating for the draft 7 and haven't encountered any errors yet ;)
But with the template language we could switch the draft version without it affecting the schemas.
What do you think @olinux?