Don't exclude results with incomplete information from results.

Make any predicates required for filters, results, or sorting optional.

Change-Id: I5a506999b40746d095d6969c4e61c90543982bb0
Reviewed-by: Christopher Adams <chris.adams@jollamobile.com>
Reviewed-by: Robin Burchell <robin+qt@viroteck.net>
MER: Add packaging.

Change-Id: I1e942440b902a89910efe120b71653fe6ae390df
[tracker] updated for tracker-sparql-0.18 buildrequires
[packaging] Fix build for Qt 5.2
[tracker] updated for tracker-sparql-1.0 buildrequires