Bug 14721: OAI-PMH must return error when no results

Bug 14721: OAI-PMH must return error when no results

When getting records from OAI-PMH, an error must be returned if there is no results.

See : http://www.openarchives.org/OAI/openarchivesprotocol.html#ErrorConditions

Test plan :
- Enable OAI webservice
- Perform a query that will return no results. ie : /cgi-bin/koha/oai.pl?verb=ListRecords&metadataPrefix=marcxml&from=2099-12-30&until=2099-12-31
=> Without patch you get a response with :
   <ListRecords/>
=> With patch you get a response with error code :
   <error code="noRecordsMatch">No records match the given criteria</error>
- Check a good query returns still results
- Same test with ListIdentifiers verb

Signed-off-by: Mirko Tietgen <mirko@abunchofthings.net>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>