Merge pull request #5261 from LaurentGoderre/master

Restored responsivness for the YouTube player
Form validation: Pluralized legend on checkbox example (fixes #5262)
Merge pull request #5267 from pjackson28/changecheckboxlegend

Form validation: Pluralized legend on checkbox example (fixes #5262)
Menu: Removed underlining on menu hover where sub-menu is present (fixes #4914)
Merge pull request #5270 from pjackson28/changemenuhover

Menu: Removed underlining on menu hover where sub-menu is present (fixes #4914)
Menu: Changed down triangle to chevron (fixes #5272)
Merge pull request #5276 from pjackson28/changemenutriangletochevron

Menu: Changed down triangle to chevron (fixes #5272)
SCSSLint: Bump to 0.23.1

New rules have been added that we can take advantage of
SCSSLint: Combine duplicate root selectors
SCSSLint: Remove unnecessary units

Sass already converts floats for division
SCSSLint: Apply PropertySort order

Basic alpha sorting for now
- Greyscale hack in tabs Sass requires it to be excluded
- Fixed but in slider SCSS with missing `@` for keyframes value
Build: Bump and target Autoprefixer

Don't vendor prefix IE8 files, and don't use IE8 hacks on the modern
sheets
Merge pull request #5279 from nschonni/autoprefixer-ie8

Build: Bump and target Autoprefixer
Merge pull request #5278 from nschonni/scss-lint-0.23.1

Scss lint 0.23.1
Menu: Decreased size of down chevron
Tables: Changed sort icons (fixes #5209)
Overlay: Fixed incorrect overlay border in IE8 (fixes #5274)
Lightbox: Fixed inner padding of AJAX modal dialog (fixes #5265)
Merge pull request #5280 from pjackson28/restoremenuchanges

Menu: Decreased size of down chevron
Merge pull request #5283 from pjackson28/lightboxinnerpadding

Lightbox: Fixed inner padding of AJAX modal dialog (fixes #5265)