Bug 16245: RIS export file type incorrect

Bug 16245: RIS export file type incorrect

When exporting lists to a RIS file, the TY field of the RIS file is always
'book' even if the item being exported is a journal or serial.
Since unimarc and marc21 is coded in Koha, just a few references types are
included. This needs a much better code.

This bug changes only TY BOOK result. Other resources needs a case by case
basis.

To test:
-In advanced search limit by itemtype (books, music, continue resources, etc).
-Search and save result in Cart
-Export to RIS Format and notice about the new TY change with all materials
-Export record in bib record details page in OPAC and Intranet.
-Confirm that works as expected.
-Bonus test:
-Try to import the  RIS file in  http://www.myendnoteweb.com if you
have account or create one.
NOTE: According with previous comment, some values has changed.

Sponsored-by: Universidad de El Salvador
Signed-off-by: Chris Cormack <chrisc@catalyst.net.nz>
Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
(cherry picked from commit a74329af022eeb857e1f936c13274c0e41497472)
Signed-off-by: Frédéric Demians <f.demians@tamil.fr>