Add attribution model identifier to quality program

Clarify that the quality program profile is used to establish a "release" of a quality program, including discussion about use of the DaVinci ATR implementation guide to establish provider attribution models and lists. In particular document that the contract-identifier is not specified as part of the quality program release, it would need to be specified elsewhere as part of the agreement between specific senders/receivers and that is the identifier that would need to be used as input to the DaVinci ATR API calls to retrieve a Group that would subsequently be used as a parameter to $evaluate-measure and $care-gaps operations. Include in the guidance that it is a potential (not prescriptive from the perspective of QM IG), and link specifically to the workflows: http://build.fhir.org/ig/HL7/davinci-atr/usecases.html#member-attribution-list-workflows-and-definitions And note the reference to "contract identifier" However, the ATR does not allow use of the contract identifier to look up a group. Would need to add a tracker to ATR to clarify how to use a contract identifier to find a group. This discussion should be added to an attribution section of the measure conformance page: http://build.fhir.org/ig/HL7/cqf-measures/measure-conformance.html