uncomment Excluded JS/CSS for JS compression in templateDetails.xml

Hi, when doing the dutch translation I translated a field that I didn't find in the template manager: jscss_excluded
been working on the SEO of my website and enabled JavaScript compression just to find out that one js script stopped working... I want to use JavaScript compression AND exclude this one script.

Found out that the jscss_excluded was commented out from templateDetails.xml. this pull request is to get it back in and working.

Just to let you know that it actually works :) got my Google pagespeed insight up to 95/100!!!