Document that alerts are removed from the DOM when closed; fixes #14318
bump grunt-autoprefixer to ~1.0.0
Merge pull request #14332 from hnrch02/clarify-alert-removal

Document that alerts are removed from the DOM when closed; fixes #14318
Merge pull request #14334 from twbs/update-autoprefixer

bump grunt-autoprefixer to ~1.0.0
Make grunt concat js files when watching
Merge pull request #14336 from michaeljayt/patch-2

Make grunt concat js files when watching
Tabs plugin accessability

Adds support for aria-expanded toggling via javascript. Adds
aria-controls, aria-expanded, and aria-labelledBy to tabs docs.

Adds unit tests for aria-expanded on tabs.

references issue #13554
Collapse accessability

Added tab-role, aria-selected, and aria-controls into the collapse html
docs.

Added support for toggling aria-expanded, aria-selected, and
aria-hidden via the javascript collapse events.

References issue #13555.

Sweet example at
http://accessibility.athena-ict.com/aria/examples/tabpanel2.shtml