Add publisher field (release schema)

[kindly]

Optionally a record/release should be able to have embedded within it the following properties.

• packageURI
• publishedDate
• publisher
• license
• publicationPolicy

This is important for API usage where all the releases/records do not belong to the same package or even belong to the same publisher. This is important as the API user should have easy access to this information (especially things like the licence).

These items most likely should be under a new property called possibly "packageMetadata"
An example release with this property would look like:

{   
    "language": "en",
    "ocid": "ocds-213czf-000-00001",
    "id": "ocds-213czf-000-00001-05-contract",
    "date": "2010-05-10T10:30:00Z",
    "tag": [
        "contract"
    ],
    "initiationType": "tender",
    ...
    "packageMetadata": {
         "uri":"http://a.com/ocds-213czf-001-01-planning.json",
         "publishedDate":"2009-03-15T14:45:00Z",
         "publisher": {
             "scheme": "GB-COH",
             "uid": "09506232",
             "name": "Open Data Services Co-operative Limited",
             "uri": "http://standard.open-contracting.org/examples/"
          },
         "license":"http://opendatacommons.org/licenses/pddl/1.0/",
         "publicationPolicy":"https://github.com/open-contracting/sample-data/"
}

These properties should be excluded from the merging process when creating the versionedRelease/compiledRelease, as it is possible for a record to have many source packages. Nonetheless, the record itself could have a "packageMetadata" property also.

This could be considered as an extension (but a standadized one) and not part of the core standard as it is optional.

[timgdavies]

This can be worked out outside of 1.1, more in relation to API standardisation.

[jpmckinney]

Noting a need for this was expressed in the context of a government having multiple authors of releases, and needing to trace back which entity authored a release within a package.