Bug 20053: Drop type attribute "text/javascript" in OPAC templates

Bug 20053: Drop type attribute "text/javascript" in OPAC templates

This patch is a reimplementation of the original from Indranil Das Gupta
and the QA follow-up from Julian Maurice. Original test plan:

Conformance rules for HTML5 is generating warnings for <script> element
with type="text/javascript" attribute when the OPAC page is checked
with W3C Validator. This patch removes the cause of these warnings.

Test plan
=========

1/ Paste the URL to your OPAC page (if it is hosted) to W3C Validator
   and watch about 10+ warnings being generated by the validator.

2/ Apply patch and re-submit the page to the Validator. The warnings
   would be gone.

Signed-off-by: Jon Knight <J.P.Knight@lboro.ac.uk>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Nick Clemens <nick@bywatersolutions.com>