Bug 11349: Change .tmpl -> .tt in scripts using templates

Since we switched to Template Toolkit we don't need to stick with the
sufix we used for HTML::Template::Pro.

This patch changes the occurences of '.tmpl' in favour of '.tt'.

To test:
- Apply the patch
- Install koha, and verify that every page can be accesed

Regards
To+

P.S. a followup will remove the glue code.
Bug 11349: remove unnecesary name translation

Since all scripts use the '.tt' sufix for template names
there's no need for and regexp that changes from '.tmpl'
to '.tt'.

Regards
To+