item rework: do not allow bulkedit to update items

item rework: do not allow bulkedit to update items

This patch is meant to guarantee that a bulkedit
does not try to edit an item tag embedded in a MARC
biblio without updating the items feature.  It is
not a comprehensive fix of the bulkedit feature, which
currently does not appear to be functional and
needs some thought:

* The general search results is probably not the
  best place to put this feature -- it should
  probably be in tools.
* A bulk edit of something like items is desireable,
  but needs to be designed so that it respects
  business logic for circulation and acquisitions.

Signed-off-by: Chris Cormack <crc@liblime.com>
Signed-off-by: Joshua Ferraro <jmf@liblime.com>