LP#1246371: Allow BibCommon::title_is_empty to accept a bre id or bre object.

I was trying to delete copies with the record fleshed in the call number
object and got the following error:

Can't use an undefined value as an ARRAY reference at
/usr/local/share/perl/5.14.2/OpenILS/Application/Cat/BibCommon.pm line 399

Having title_is_empty check for a bre object and use its id solved this
problem for me.

Signed-off-by: Jason Stephenson <jstephenson@mvlc.org>
Signed-off-by: Galen Charlton <gmc@esilibrary.com>