Add a `q` query parameter to query against all fields

This is a proposed fix for #184

Deployed to staging: http://staging.api.lobid.org

Check out the new `q` parameter column on the index page, and the usage samples, which now use the `q` parameter for getting suggestions.

The queries with `q` use the OR operator, but retain the ranked sorting order for all results, including the suggestions. That way, "Bundesinstitut für Arzneimittel und Medizinprodukte (BfArM), Abteilung „Forschung“, 53175 Bonn" on the organisations suggestion field will return results, and the closest hit is on top.