SEO: Assure swisssearch parameter results are visible

This PR make sure that swissearch parameter results are visible to the webcrawlers. This can potentially be powerful to index pages containing both names and geodata.

E.g. A page like http://map.geo.admin.ch/?swisssearch=bern&layers=ch.swisstopo.swisstlm3d-wanderwege will be indexed with keywords 'Bern' and 'Wanderwege'.