Call qmlRegisterUncreatableType for Marble::MarbleMap

Summary:
QtQml 5.3 seems to need this even for passing just Marble::MarbleMap* values
between objects, without accessing any properties of Marble::MarbleMap

Reviewers: nienhueser

Reviewed By: nienhueser

Projects: #marble

Differential Revision: https://phabricator.kde.org/D579