(less) Merge branch '3.0.0-wip' of https://github.com/saas786/bootstrap into saas786-3.0.0-wip

Conflicts:
	customize.html
	less/alerts.less
	less/badges.less
	less/button-groups.less
	less/buttons.less
	less/carousel.less
(less) Merge pull request #9124 from geedmo/3.0.0-wip

 Fix Issue #8175 - .input-group-addon broken in Firefox
(less) remove dupe border-box
(less) Merge branch '3.0.0-wip' of github.com:twbs/bootstrap into 3.0.0-wip
(less) fixes #8647: remove focus outline on :focus of buttons in button groups
(less) Merge branch '3.0.0-wip' into bs3_alerts_default_class

Conflicts:
	dist/css/bootstrap.min.css
(less) Scope tablet classes to tablets range only

Fixes #9128
(less) Fixes #9145: Fix tooltip opacity

Update tooltips to not use RGBa colors so IE8 can have tooltips, too
(means we're now using `opacity`).
(less) fixes #9140: use correct var in tables
(less) Merge pull request #8731 from nrw/patch-1

Format multiple badges in list-group-item
(less) Fix #9174: pad bottom of navbar collapsed content and clear floated contents
(less) Fixes #8749: prevent navbar nav from overlapping navbar toggle
(less) Merge branch '3.0.0-wip' of https://github.com/archanl/bootstrap into archanl-3.0.0-wip

Conflicts:
	less/mixins.less
(less) update use of mixins and add bg-colors where necessary
(less) Merge branch '3.0.0-wip' into bs3_theme

Conflicts:
	dist/css/bootstrap.min.css
(less) more twerks to the theme
(less) fixes #8935: add gutter width param to grid mixins
(less) fixes #8959: only negative indent rows within .container (prevents horizontal scroll on full-width pages)
(less) Improve accessibility (Section 508, WCAG)

This PR significantly improves Bootstrap's accessibility for users of assistive technology, such as screen readers. Some of the these changes add additional markup to the source examples, but we believe that the sacrifice in readability is worth achieving more widespread usage of accessibility best-practices.

What was done
- Added lots of [WAI-ARIA attributes](http://www.w3.org/WAI/intro/aria)
- Added `.sr-only` helper class, that is only readable by screen readers (and invisible for all other users). This lets us - make progress bars and paginations accessible to screen reading users.
- Advised users to always use label elements. For inline forms, they can hide them with `.sr-only`
- Added 'Skip navigation' link
- Added "Accessibility" section to getting-started.html.

What *wasn't* done
- Contrast issues (twbs#3572)
- Tooltips (twbs#8469)
- Documentation re: usage of icons, since they now live in a separate repo

Major props to all that contributed: @bensheldon, @jasonlally, @criscristina, and @louh. Feel free to chime in, guys, if I've left anything out.
(less) property order