Bug 21801: (follow-up) Use ->account

This patch is a minor refactoring, that reuses the $account object we
already get from $patron, instead of creating new ones all over the
place. Code gets simpler to read too.

Signed-off-by: Mark Tompsett <mtompset@hotmail.com>
Signed-off-by: Josef Moravec <josef.moravec@gmail.com>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>