Bug 8378 - <fine> in overdues changed to <<items.fine>>

Bug 8378 - <fine> in overdues changed to <<items.fine>>

This patch reintroduces fines in overdue_notices.pl with minimal
changes to exsiting code.

It DOES changes template syntax, it used to be <fine>USD</fine> but
currency was not recalculated and used only to select format, so
now we are using active system currency because values are in it
anyway.

Example notify template:

<item>"<<biblio.title>>" by <<biblio.author>>, <<items.itemcallnumber>>,
Barcode: <<items.barcode>> Fine: <<items.fine>> </item>

If your active currency doesn't have valid ISO code this code will
fallback to sprintf with two decimal digits, and you can insert
currency symbol in template itself (currency field is not editable
through web interface, so this fallback might be useful for existing
installations).

Test scenario:
1. configure fine amount under "Circulation and fines rules"
   for patron category and item type
2. checkout item with correct type to partron in correct
   category with due date set to yesterday
3. verify that overdue notice uses new <<items.fine>> tag
4. run ./misc/cronjobs/fines.pl to calculate fines
5. run ./misc/cronjobs/overdue_notices.pl -n
   and verify that fine amount is included

Notes: Tested using the default ODUE notice, changing:
<fines>USD</fines>
for
<<items.fine>>

Everything worked as expected with finesmode=production set.

Signed-off-by: Tomas Cohen Arazi <tomascohen@gmail.com>
Signed-off-by: Jonathan Druart <jonathan.druart@biblibre.com>
Signed-off-by: Jared Camins-Esakov <jcamins@cpbibliography.com>