Bug 21874: Fix encoding of cart and list email subjects

Bug 21874: Fix encoding of cart and list email subjects

The subject of the cart and list emails is not correctly
encoded and displays incorrectly in some email clients.

To test:

Lists:
- Create a list, name it using umlauts or other diacritics
  Example:  Jugendbücher (books for youths in German)
- Add some items to your list
- Email yourself the list
- Verify that the email subject is broken

Cart:
- Install another language with non-latin characters like Greek
- Fill the cart with some titles
- Send yourself the cart
- Verify that the email subject is broken

Note: Some email clients display correctly, others not.
      It's known to be incorrect in Outlook and web.de,
      displaying nicely in Thunderbird.

Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Tested all four scripts by manipulating the cart text too in templates.
Follow-up handles intranet sendshelf.

Note: I asked Katrin to remove the encode UTF-8 statements, since we
convert to MIME and the subject line should never be UTF-8.

Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Nick Clemens <nick@bywatersolutions.com>