Tile cache versioning for Nokia maps

Added to avoid mixing of different map versions in map view.

Generic cache versioning by adding an incremental version number to
tile specs and filenames. Default version -1 falls back to not using
version in file names for backward compatibility.

Nokia specific version management by implementing the version request,
comparing all version information and increment the version if anything
has changed.

Task-number: QTBUG-25559
Change-Id: I6820f2efbe7458701475cc833d3077022797b2df
Reviewed-by: Alex Blasche <alexander.blasche@digia.com>