Bug 19353: Ability to use xsl template on marc21 and marcxml metadataprefixes in...

Bug 19353: Ability to use xsl template on marc21 and marcxml metadataprefixes in OAI provider

Test plan:
0) apply the patchset
1) setup oai server with oaiconf file defining xsl_file for metadata
format marcxml or marc21
2) play with your oai and confirm that records are transformed as
expected
3) prove t/db_dependent/OAI/Server.t

Signed-off-by: Martin Šťastný <martin.stastny@teamlibrary.cz>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>