title: Datatables Sorting Styles being incorrectly applied to header
body: <p>I am having an issue after updating from 1.9 to 1.10 in the the header sorting styles seem to be applied to both  and the inside the sort_wrapper div which is inside the  this is causing a dark background to cover the entire head (<a href="https://i.stack.imgur.com/hiVLL.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/hiVLL.png" alt="Bad Header"></a>) as opposed to in 1.9 where it was only applied it inside the sort wrapper (<a href="https://i.stack.imgur.com/gny0z.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/gny0z.png" alt="Good Header"></a>) I have tried setting "orderClasses": false in the init object but it seems to make no difference
  Any Ideas?</p>