Merge pull request #12983 from twbs/fat-9836

fixes #9836
Merge branch 'master' into sr-only-focusable

Conflicts:
	dist/css/bootstrap.css
document position relative firefox bug; cleanup some stuff in the browser bugs page
grunt
Remove unneeded quotes.
Don't ignore every dot file in Bower
Merge branch 'master' into sr-only-focusable
Merge pull request #12679 from twbs/sr-only-focusable

add .sr-only-focusable
grunt
Merge pull request #12989 from twbs/bower_ignore

Don't ignore every dot file in Bower
Document #12476 bug in the wall of bugs
Merge branch 'master' of github.com:twbs/bootstrap
Document shitty situation of multiple .navbar-right classes in #12951
Fixes #12487: Document required use of position relative for scrollspy
Moves IE8 justified button border mention to docs section, not the browser bugs page /cc @cvrebert
Fixes #12892: Link to one of the SO articles on Bootstrap modals and YouTube
Merge pull request #12986 from twbs/unneeded-quotes

Remove unneeded quotes.
Reorder the Gruntfile a bit
Merge branch 'master' of github.com:twbs/bootstrap

Conflicts:
	Gruntfile.js
Adds basic table of contents for mixins.less. You know for the kids.