Bug 5327 - Adding UNIT Tests.

Bug 5327 - Adding UNIT Tests.

Squashed commit of the following:

commit 146d14665c52edaa85e38b70aabc9d52be5d64b6
Author: Zach Sim <joseph.zachariah.sim@gmail.com>
Date:   Mon Jan 17 16:07:24 2011 +1300

    Edited DisplayISBN to cleanup the ISBN using _isbn_cleanup if it is not 13 or 10 digits long.

commit ba97b26d9a25470b0717cdd60a3d4f7a5c459ca9
Author: Zach Sim <joseph.zachariah.sim@gmail.com>
Date:   Mon Jan 17 16:06:14 2011 +1300

    Added extra unit tests to test C4::Koha::DisplayISBN.

Signed-off-by: Chris Cormack <chrisc@catalyst.net.nz>