Add role="tabpanel" to .tab-pane <div>s to improve accessibility

BS3 commits: a53be21b45b4521a512e3b63a59608c1d20a82c9
add role="presentation" to tab <li>s to improve accessibility

BS3 commits: 4683beeedf0e4d923f1556199f4d23d7d35bccea
add role="tabpanel" to .panel-collapse to improve accessibility

BS3 commits: 9ff2c911a3b8fd80063a2bedeb2a378519e2f392
Add role="tablist" & aria-multiselectable="true" to accordion .panel-group

BS3 commits: 8c6061c1950f2bcd14baf8be549c3e532bd498cd