BUG 9145: Authorities: standard language for UNIMARC

BUG 9145: Authorities: standard language for UNIMARC

New Authority system preference created UNIMARCAuthorityField100 with default value "afrey50      ba0".
AuthoritiesMarc.pm uses the system preference instead of label "afrey50      ba0".

Signed-off-by: Jonathan Druart <jonathan.druart@biblibre.com>
Signed-off-by: Katrin Fischer <Katrin.Fischer.83@web.de>
Works as described, all tests and QA script pass.

1) Check system preference is created correctly.
2) Change pref.
3) Catalog a new authority.
4) Change framework to make 100 show in frameworks or check in the
   the database, that now 100 has the new defined value.
Signed-off-by: Jared Camins-Esakov <jcamins@cpbibliography.com>