Bug 6373 : Corrects a validation problem on addbiblio.pl on IE8

Bug 6373 : Corrects a validation problem on addbiblio.pl on IE8

The mandatory fields popup didn't appear when some mandatory fields
weren't filled on IE8. Replacing the "focus" with its JQuery equivalent
corrected the problem.

[EDIT by Owen Leonard] Removed commented line

Signed-off-by: Owen Leonard <oleonard@myacpl.org>
Follow-up by owen, that he forgot to upload on bugzilla:

Signed-off patch includes one minor edit: I removed the commented-out line

which the jQuery line replaces. We have git to track changes for us, we don't
have to leave old code in.

Signed-off-by: Paul Poulain <paul.poulain@biblibre.com>
Signed-off-by: Chris Cormack <chrisc@catalyst.net.nz>