Fixes #14319: Prevent jumbotron reflow by ensuring padding of .container isn't interferred with by .jumbotron side padding
customizer: minor cleanup of IE8 error messaging code

[skip sauce]
Merge pull request #14563 from twbs/fixes_14319

Fixes #14319: Jumbotron reflow
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