cubicweb #2168112 Implement opensearch [open]

OpenSearch is a standard for searching on websites. Once this is implemented, the search function on a website can be integrated easily. For example in the Firefox search bar.

See https://en.wikipedia.org/wiki/OpenSearch & http://www.opensearch.org/Home

Further more https://en.wikipedia.org/wiki/Search_aggregator makes me think of a standard way to search across various cubicweb instances, which could be a killer feature.

prioritynormal
typeenhancement
done in<not specified>
closed by<not specified>