Bug 18183: jQuery append error related to script tags in cloneItemBlock

Bug 18183: jQuery append error related to script tags in cloneItemBlock

See the detailed explanation of the error on Bugzilla.
As a workaround, we move the append of clone to outeritemblock before the
append of data (long string with item fields and script tags) to clone.

This patch also moves two vars inside the success function, since they are
not used outside of it.

Test plan:
[1] Set AcqCreateItem to receiving.
[2] Receive an order. Verify that adding, updating or deleting an item block
    still works as expected.

Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Josef Moravec <josef.moravec@gmail.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>