Bug 13952: (follow-up) Fixing authority type import

Bug 13952: (follow-up) Fixing authority type import

This patch fixes the comments from Comment 29 and the import
functionality. You should now be able to import an exported file without
editing the file at all and the authority type code will be overwritten
in the file (same behaviour as biblio frameworks).

Sponsored-by: Catalyst IT
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Michal Denar <black23@gmail.com>
Signed-off-by: Michal Denar <black23@gmail.com>
Signed-off-by: Mazen Khallaf <mazen.i.khallaf@gamil.com>
Signed-off-by: Michal Denar <black23@gmail.com>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Fridolin Somers <fridolin.somers@biblibre.com>