Remove sparql directory
Implement early basic sqlite database code

Includes basic creation of the database, porting of the models. It's
possible to add and list groups, events, and calls in a basic way.

Most of the database behavior is stubbed out, and many things are
disabled or broken.

QStandardPaths is used for the database location, or a hardcoded
equivalent on Qt4.
Remove tracker database and sparql query code
Remove QtSparql dependency
Fix build of tests
Add more SQLite database function implementations

Includes some API/ABI changes as a result of now-useless functionality.
Use a basic query builder for event/group properties
Improve CallModel filters API and add account filtering
[libcommhistory] Bump soversion to 1.6.0 due to API/ABI changes
Remove old grouped call query logic from CallModel

This is unnecessary and tracker specific. If further work is required to
make contact grouping in CallModel work later (which doesn't seem to be
the case currently), it won't be done like that.
Minor porting tweaks