Bug 12851: order tags should be removed from the claiming letter

Bug 12851: order tags should be removed from the claiming letter

If you use a claimissue notice to claim serials, the generated letter
will be

<order>Title1, Author1</order>
<order>Title2, Author2</order>
...
<order>TitleN, AuthorN</order>

This patch geds rid of these tags.

Test plan:
1/ Create a claimissue notice with something like:
  <<LibrarianFirstname>>
  <<LibrarianSurname>>
  The following issues are in late:
  <order><<biblio.title>>, <<biblio.author>> (<<biblio.serial>>)</order>

2/ Generated late serial issues.
3/ Send notifications to vendor.
4/ The order tags should not exist anymore in the sent email.

You can see bug 5342 for a more detailled test plan.

Note for QA: This should have been done in GetPreparedLetter, but I did
not find a better way to do.

Signed-off-by: Paola Rossi <paola.rossi@cineca.it>
Signed-off-by: Katrin Fischer <Katrin.Fischer.83@web.de>
Works as described. Tested having the <order> tags on one line
and also for a multi-line layout.

Signed-off-by: Tomas Cohen Arazi <tomascohen@gmail.com>