Add Embed responsive utility
fix #12154
Merge branch 'responsive-embed' of https://github.com/boulox/bootstrap into boulox-responsive-embed

Conflicts:
	dist/css/bootstrap.css.map
	dist/css/bootstrap.min.css
fix #12007 by clarifying target of dropdown events
refactored and renamed grid mixins
fixed first element padding of list-inline
Added .list-group-item.disabled

Added support for disabled List group item.
Update variables.less
rm callout about creating .container-fluid-alikes now that .container-fluid has been added
Remove redundant :-moz-placeholder styles

No need for old Firefox versions support.
fixed two typos in carousel.less

carousel.less has two typos in glyphicon classnames. fixed them.
Sticky footers without any wrappers
Added border radiuses to table when in a panel. Fixes #12461
use :extend in thumbnail Less
use :extend(.img-responsive) in Carousel's Less
Merge pull request #12621 from twbs/carousel-img-responsive-extend

use :extend(.img-responsive) in Carousel's Less
Merge branch 'master' into thumbnail-extend

Conflicts:
	dist/css/bootstrap.css
Merge pull request #12502 from ZDroid/moz

Remove redundant :-moz-placeholder styles
Merge pull request #12620 from twbs/thumbnail-extend

use :extend in thumbnail Less
property order because @zdroid <3