Issue #41: Interviewer management

Suggestion from informal discussions during the 2016 standards workshop: "GSIM could be extended to cover interviewer management"

For me, this is on the borderline of the GSIM scope, as defined in the V1.1 Communication Paper: "GSIM provides the information object framework supporting all statistical production processes such as those described in the GSBPM ... GSIM does not include information objects related to business functions within an organization such as human resources, finance, or legal functions, except to the extent that this information is used directly in statistical production."