Fix footer links
Adapt about.html lead to latest changes
Fix customizer's toggle buttons' margin
fix ad placement
Merge branch 'master' of github.com:twbs/bootstrap

Conflicts:
	docs/assets/css/pack.min.css
reassert #12231 & #12232 (merge went badly?)
add Issues & Releases links back to footer
refactoring: add & use .text-emphasis-variant() mixin
refactoring: add & use .bg-variant() mixin
add & use @modal-md Less var for uniformity
Merge pull request #12245 from twbs/footer-links

add Issues & Releases links back to footer
update browserstack-runner package
add debug for browserstack-runner
Merge pull request #12252 from browserstack/browserstack-runner

Browserstack runner tunnel timeout
Fixing js error in IE9 where no transition is supported
Merge pull request #12258 from ibash/master

Fixing js error in IE9 where no transition is supported
Update javascript.html

Fixed issue in Tabs example where the div had been marked as 'active' but the li had not been.  The correct tab of data would be displayed on load, but no tabs would be highlighted.  The tabs with fade example does not have this issue.  jsFiddle: http://jsfiddle.net/uXV56/
Merge pull request #12260 from patricker/patch-1

Update javascript.html to fix Tabs example
new qunit
remove flaky pos bottom test which is effect by unit scroll pos