add role="tab" to .panel-heading-s in accordion example to improve accessibility

BS3 commits: 60164bc4ba33b4b8132629ebaf781b72266a7979
add aria-labelledby to accordion example to improve accessibility

BS3 commits: 0fe48a78c105410ec5abac88418f3395b245e33c
grunt. Teh grunt. grunt

BS3 commits: 0cf94b82ee49aa1b2f65495f87945ad3af51354f,
0a4c39dc40e16a3aa18721bf78935e77ac11f097,
d0f76e416cda07ad98e5ee6d91d132b580c9d051