releasability 2.0

[stansmith907]

Changes:

1. MD_Releasability is a new class. Definition: “information about resource release constraints.”
2. “addressee” is an array of type CI_Responsibility. Definition: “party to which the release statement applies.” Issue responsibility 2.0 #52.
3. “statement” is a scalar text filed. Definition: “release statement.”
4. “disseminationConstraint” is a array of MD_RestrictionCode. Definition: “component in determining releasability”.
5. The "releasability" record must have at least one "addressee" or "statement".

      "releasability": {
         "addressee": [
            "see responsibility 2.0"
         ],
         "statement": "",
         "disseminationConstraint": [
            "MD_RestrictionCode"
         ]
      },

see XML example useConstraint -3.xml