Extend selfCloseHtmlTags

  * [menuitem](http://www.w3.org/html/wg/drafts/html/master/interactive-elements.html#the-menuitem-element)
  * [track](http://www.w3.org/html/wg/drafts/html/master/embedded-content.html#the-track-element)
Merge pull request #40 from greyevil/master

Extend selfCloseHtmlTags