Crossrefutils: Configuraion variable for crossref2marcxml.xsl

 * configutaion changes in crossref2marcxml.xsl and crossrefutils.py

 * change in crossref2marcxml.xsl for linking templates in /opt/invenio/etc/bibedit/record_templates/

 * new variable CFG_CROSSREF_2MARC in invenio.conf for crossref2marcxml.xsl

 * change in crossrefutils.py for new variable

 * final commit after cleaning logs

 Signed-off-by: Nalin Chhibber <nalin.chhibber@gmail.com>
 Acked-by: Javier Martin Montull <javier.martin.montull@cern.ch>