Bug 12032: disable automatic URL conversion by TinyMCE in news

Bug 12032: disable automatic URL conversion by TinyMCE in news

To test:

* create a news item with a link in it that is within the same domain

example: my koha was at http://demo.mykoha.co.nz, I created a link in a
news item to http://demo-intra.mykoha.co.nz

* note that when the item is saved, the url changes to ../../../../ (or
something like)

* apply the patch

* edit the link again, and save it

* note that the link is saved correctly

Signed-off-by: Owen Leonard <oleonard@myacpl.org>
Signed-off-by: Katrin Fischer <Katrin.Fischer.83@web.de>
Passes all tests and QA script.

Signed-off-by: Galen Charlton <gmc@esilibrary.com>
(cherry picked from commit 3fc5aeb7456fbda97b6fbc0fb66ddbc3aa253439)
Signed-off-by: Fridolin Somers <fridolin.somers@biblibre.com>