[skeleton-v3] Pull frontend dependencies from source

[themightychris]

@ryon please document here the repos/branches you pulled vendor libs from, I want to set up hologit links for each so we can control vendor lib upgrades there going forward

[ryon]

lib	source
bootstrap.js	https://github.com/twbs/bootstrap/blob/master/dist/js/bootstrap.js
jquery.filedrop.js	https://github.com/weixiyen/jquery-filedrop/blob/master/jquery.filedrop.js
jquery.js	https://github.com/jquery/jquery-dist/blob/master/dist/jquery.js
markdown.js	I’m not sure, maybe https://github.com/jjclark1982/markdown ?
popper.js	https://unpkg.com/popper.js/dist/
prism.js	[Customized download]
bootstrap.scss	https://github.com/twbs/bootstrap/blob/master/dist/css/bootstrap.css
prism.scss	[Customized download]

Font Awesome info TK