Identifier.assigner shall be Reference(Organization)

[yunwwang]

According to FHIR standard (http://hl7.org/fhir/datatypes.html#Identifier), Identifier.assigner is a type of Reference(Organization).

This is what generated from crucible:

                              "assigner": {
                                  "type": "http://projectcrucible.org/YSKPwltOMWyed4YJvx9EOw==",
                                  "identifier": {
                                      "use": "temp",
                                      "type": {
                                          "coding": [
                                              {
                                                  "system": "http://terminology.hl7.org/CodeSystem/v2-0203",
                                                  "code": "PLAC",
                                                  "display": "Placer Identifier",
                                                  "userSelected": false
                                              }
                                          ],
                                          "text": "cVtFOkgvTBPsOL+DeQThpQ=="
                                      },
                                      "system": "http://projectcrucible.org/ZBldZruO+pZj/gvKn9F+Yg==",
                                      "value": "CNXHeYtLT/nh289eUI8ccg=="
                                  },
                                  "display": "Organization Oj3geCRHwHw9DJ1pm1mOtA=="
                              }