Summary: So that it can be integrated in QtQuick applications

Test Plan: Implemented it Discover, everything seems to work

Reviewers: vkrause

Reviewed By: vkrause

Differential Revision: https://phabricator.kde.org/D5960

This protects tracking of already completed surveys against SQL auto id
reuse, making it safe to delete and re-create surveys.

We now have API for getting notification about a survey, and we can check
if a survey has been completed already.

Listing works, creating partially works, update/delete still missing.

So far we can track basic usage statistics and report them to the server,
create and delete products on the server, and look at the raw data using
the analyzer tool.