fix user session management for MARC Batch Edit

The Javascript in the hardcoded page templates was
not checking the XUL stash for the session key when
run from the staff client; this is now needed as
a result of the XULRunner updates introdued by
commit adee850f.

As a consequence, the list of the user's record buckets
was not retrieved, and attempts to run a batch edit
would spin without updating any records.

This fixes LP#1048707 and LP#1054277.

Signed-off-by: Galen Charlton <gmc@esilibrary.com>
Signed-off-by: Mike Rylander <mrylander@gmail.com>