Fix bug #12910134 Implement Search into the Settings App

- optimize MATCH query. Basically instead of doing 3 UNIONs,
we are building a more clever MATCH query that can search on
data_title OR data_summary OR data_keywords.
- the consequence is that the generated SQL should be way more
efficient to process and should also get the results faster.
- last, as the generated SQL is shorter, it will be easier to
understand and debug for Humans :-)

Change-Id: I0f71740cae86b8c95ed88f9a5d13b8b4c860b1a9