Add CoreLocation positioning plugin for QtLocation

Implements a QGeoPositionInfoSource plugin using CoreLocation.

Implemented by Ian Dean.

[ChangeLog][QtPositioning][QGeoPositionInfoSource] iOS position backend
added.

Change-Id: I09df434f95e5d72b1f6cf6381412334ae45d3d54
Reviewed-by: Ian Dean <ian@mediator-software.com>
Reviewed-by: Alex Blasche <alexander.blasche@digia.com>