Fixes #556. Adds new LoC relators and script to convert from old

[drn05r]

As this will be applied if someone upgrades, it is probably best it does not break things, so by default it should stick with the old LoC relators and

• Adds new LoC relators in lib/namedsets/contributor_types.new
• Renames old LoC relators in lib/namedsets/contributor_types.old
• Adds symlink for lib/namedsets/contributor_types to lib/namedsets/contributor_types.old
• Retains old LoC relator phrases as well as adding new LoC relator phrases.
• Adds script to convert from old to new contributor types. By default it will only update the contributors field for eprint data objects
• Updates RDF BIBO export to use http://id.loc.gov/vocabulary/relators/edt rather than www.loc.gov version.
• Updates Import::DOI plugin so new relators can be switched to if doi_contributor_types.pl.disabled is enabled.
• Does not update Export::OAI_UKETD_DC but adds new thesis advisor LoC relator to doi_contributor_types.pl.disabled.