Merge pull request #9973 from coliff/patch-6

Update justified-nav.css (Removed unnecessary ms-linear-gradient prefix)
fix #9941
change `else if` to `else`
code.less: also set default monospace font for `<kbd>` and `<samp>`
removed reference to button color and gradient

Changed the wording to reflect the default button's new look since it's no longer grey and doesn't have a gradient. I'd say this new wording isn't ideal and needs something a bit more, well, descriptive.
removed extraneous space
Merge pull request #9987 from wangsai/fix-typo

change `else if` to `else`
Fixes #9974

Added th selector in .table-row-variant mixin
Merge pull request #9999 from sqrt4/fix-9974

Fixes #9974
deprecate @screen-{phone,tablet,desktop} vars
remove .btn-group

The example doesn't use .btn-group and adding the class causes "bad things to happen," as the saying goes.

http://jsfiddle.net/josephtate/g6AWF
remove .btn-group

Removing this class--it's not used in the example and using it causes "bad things to happen." 

http://jsfiddle.net/josephtate/Jn6H4/
Merge pull request #10006 from jodytate/master

remove .btn-group
Merge branch 'master' of github.com:twbs/bootstrap
Update Grunt instruction links and wording
add David (david-dm.org) badge to monitor currentness of dependencies
Always wrap form examples in .bs-example; add some missing role='form'
Merge pull request #10011 from nschonni/patch-1

Update Grunt instruction links and wording
Fixing carousel control positioning

The left control should be positioned from the left, while the right
control should be positioning from the right. Positioning both from the
left results in the right carousel control being incorrectly positioned
(most noticeable with a larger than normal font size).
Added glyphicon-block class

Prevents elements moving around the page after the font file has loaded by setting a defined width on elements using the icon font.