Bug 14598: Make C4::Circulation::AddReturn store the right itemtype

Bug 14598: Make C4::Circulation::AddReturn store the right itemtype

This patch makes C4::Circulation::AddReturn correctly store the itemtype
on the 'statistics' table.

To reproduce:
- Checkout master.
- Make a checkout.
- Check the 'statistics' table and notice the itemtype is correctly set
  > SELECT * FROM statistics;
- Check the item in.
- Check the 'statistics' table and notice the itemtype is not set
  > SELECT * FROM statistics WHERE type="return";
=> FAIL: itemtype is set to NULL

To test:
- Apply the regression tests patch
- Run the tests:
  $ prove t/db_dependent/Circulation/Returns.t
=> FAIL: Tests fail
- Apply this patch
- Run the regression tests:
  $ prove t/db_dependent/Circulation/Returns.t
=> SUCCESS: Tests now pass.
- Repeat the 'To reproduce' steps
=> SUCCESS: itemtype is now correctly set (in real life)
- Happily sign off :-D

Sponsored-by: Universidad Empresarial Siglo 21
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
Signed-off-by: Tomas Cohen Arazi <tomascohen@gmail.com>
Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>