Return the same format as for api/issues/search, except that:
- field "issues" is replaced by "issue"
- of course there are no facets nor paging
- field "languages" is not present (that should be dropped from api/issues/search too)
- protobuf specification of response
- do not rely on ES docs to return data (will allow to remove _source
from ES index)
- sanitize response format
- sanitize request parameters (no more 'hideXXX' and 'f')
