retry each test up to 3 times in the event of timeout

Big thanks to @gvas for https://github.com/axemclion/grunt-saucelabs/pull/136 ! <3
Merge pull request #13916 from glebm/variable-order

Move variable declaration before its use (for Sass)
Merge pull request #13918 from twbs/sauce-with-retries

Enable retrying of timed-out Sauce tests
reenable OS X Chrome in Sauce
reenable Win7 IE8-9 in Sauce
Merge pull request #13781 from twbs/saucier

Reenable additional Sauce browsers
update shrinkwrap to get clean-css v2.2.3

Refs #13914
Refs https://github.com/GoalSmashers/clean-css/issues/302
Revert "Turn off clean-css' advanced optimizations."

This reverts commit 25ca51319b016bc4e42e1ba882d6f191e001d65d.
grunt dist; closes #13914
Revert "Revert "Turn off clean-css' advanced optimizations.""

This reverts commit e31c2edf885efd42d2e755f189cc15125d977d70.
Run `grunt`.

Revert a991cd572c8b3cafa6228915ca86f7a0cdd26e2d.
Allow tabs to fade in if no initially active pane is present; fixes #13814
Add a few more cases to the visual test tab page
assign background to row of .table-striped

if background is not set on row, striping doesn't work properly in responsive tables where row and cells are set to  display: block.
removing redundant background declarations on TDs
Added @gray-base variable to make @gray-{shade} reference, also allows @gray-base to be modified with less#modifyVars and the vars to cascade
Fixed @gray-base value being once space short
fixes #13912: make radios/checkboxes work with inline forms again
Merge branch 'master' of github.com:twbs/bootstrap

Conflicts:
	dist/css/bootstrap.css.map
	dist/css/bootstrap.min.css
	docs/dist/css/bootstrap.css.map
	docs/dist/css/bootstrap.min.css
Mozilla bug says the fix targeted v31