add id, scheme, uri, wasDerivedFrom properties

[odscjen]

closes open-contracting/ocds-extensions#234

[odscjen]

Renamed codelist as it's no longer an extension to the Classification object's codelist

[odscjen]

Realised needed the codelist to have the same name to allow the codes to be used in the wasDerivedFrom Classification object. No idea why it's giving an error now though, maybe because it's patching to 1.2 and in 1.2 this codelist has been renamed to classificationScheme rather than itemClassificationScheme?

[duncandewhurst]

I think you're probably right about +itemClassificationScheme.csv needing to be renamed to +classificationScheme.csv.

[odscjen]

I've left the codelist as itemClassificationScheme.csv so that it remains compatible with 1.1.5, but the answer to the tests faililng appeared to be removing the "+" sign from the start of the codelist when it's declared in the schema so I've done that

[duncandewhurst]

Ah, of course! Good catch :-)