LP#1277551: Limit simplified pull list to available copies

Copies that are targeted by a hold but are not in available or reshelving
statuses should not show up on a pull list.

Signed-off-by: Thomas Berezansky <tsbere@mvlc.org>
Signed-off-by: Michele Morgan <mmorgan@noblenet.org>
Signed-off-by: Ben Shum <bshum@biblio.org>