Bootstrap tabs WAI-ARIA attributes set for better accessibility

[bassettsj]

Again from the paypal/bootstrap-accessibility-plugin, these changes should be added to the documentation and the JS plugin.

Tab Panel

1. Add ARIA roles like tablist, presentation, and tab for tabs UL, LI.
2. Add tabIndex, aria-expanded, aria-selected, aria-controls for tab.
3. Add ARIA roles of tabpanel, tabIndex, aria-hidden, and aria-labelledBy for tabPanel.
4. Add keydown event listener for the tab to work with keyboard.
5. Dynamically flip tabIndex, aria-selected, and aria-expanded for tab when it is activated and add aria-hidden to hide the previously visible tab.

[asaf]

According to the WAI ARIA spec, it is also required to completely remove the wrapper tag for the tab panels. (the div with the tab-content class

[cvrebert]

• Need to take into account paypal/bootstrap-accessibility-plugin@f203dea

[apexskier]

Would it be acceptable to add the aria-controls attributes based on the href target of the anchors they are being applied to?