UFAL implementation of OAI-PMH for both importing (with ORE if supported...

UFAL implementation of OAI-PMH for both import and export.

Importing metadata:
- from a repository which supports the current metashare v3 format, see https://ufal-point.mff.cuni.cz/oai/request?verb=ListRecords&metadataPrefix=oai_metasharev3
Importing file contents:
- from a repository which supports ORE with minor change namely adding the actual file path info into to the metadat. The remote directory should be available locally because of licensing.

Exporting metadata:
- IdentifyServer, ListIdentifiers ready as a proof of concept and API use cases