IMPROVEMENT/FEATURE Forcefully write javascripts to the end of the HTML if wanted.
It's defaulted to false. But when set to true, the JS is written to the end of the HTML, even though there are earlier scripts.
This results in faster page-loading if the JS isn't needed earlier-on.
NEW Force the javascripts to be put before the closing body tag
Merge branch 'feature/force_write_js_to_bottom' of https://github.com/Firesphere/silverstripe-framework into feature/force_write_js_to_bottom