accessible accordion

@SiTaggart @alexmckenley 
That's what I thought too, but it didn't anything and I checked to make sure it is focused too. 

`> document.activeElement
<a class=​"accordion-title ng-binding" ng-click=​"isOpen = !isOpen" accordion-transclude=​"heading" tabindex=​"0">​Dynamic Group Header - 1​</a>​`