Bug 18477: Populate article_requests table values for AR_PENDING notices

Bug 18477: Populate article_requests table values for AR_PENDING notices

The default AR_PENDING letter does not print populate <<article_requests.*>> fields.

Test Plan:
1) Enable article requests ( syspref: ArticleRequests => Enable, Circ and fine rules ALL/ALL (or a given category/itemtype): Article requests => Yes )
2) Search for a title, click in to catalog detail, click 'Request Article' button.
3) Select Patron
4) Fill out request information
5) Click 'Place request'
6) Go to notices in patron record, inspect 'Article Request Received' notice. You should see the request information from step 4, but it doesn't display.
7) Apply this patch
8) Repeat steps 2-6, not the fields now display!

Signed-off-by: Eric Phetteplace <phette23@gmail.com>
Signed-off-by: Mark Tompsett <mtompset@hotmail.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>