Bug 17530: (QA follow-up) Move may_article_request to ItemType

Bug 17530: (QA follow-up) Move may_article_request to ItemType

As requested by QA, we should move may_article_request out of Biblio.

For reasons of performance removed the wrapper layer of may_article_request
in opac-search. No need to look up all item types. For readability kept
the routine in the detail scripts.

Note for running ArticleRequests.t: A possible failure on the subtest
'search_limited' is addressed on bug 20866. So you can ignore that one.
As long as the subtest for may_article_request passes.

Test plan:
See previous patches.

Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Signed-off-by: Chris Cormack <chrisc@catalyst.net.nz>
Signed-off-by: Nick Clemens <nick@bywatersolutions.com>