Bug 20054: Remove attribute "text/css" for <style> element in OPAC

Bug 20054: Remove attribute "text/css" for <style> element in OPAC

Conformance rules for HTML5 is generating warnings for <style> element
with type="text/css" attribute when the OPAC page is checked
with W3C Validator.

Test plan
=========

1/ Click the "Tag cloud" link on the OPAC. Paste the URL to your OPAC
   page (if it is hosted) to W3C Validator and watch the warning about
   type attribute "text/css".

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

Signed-off-by: Owen Leonard <oleonard@myacpl.org>
Signed-off-by: maksim <maksim@inlibro.com>
Signed-off-by: Julian Maurice <julian.maurice@biblibre.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>