fix(accordion): adding all supported selectors to header transclude

Author: perryhoffman

src/accordion/accordion.js

@@ -124,11 +124,21 @@ angular.module('ui.bootstrap.accordion', ['ui.bootstrap.collapse'])
     link: function(scope, element, attrs, controller) {
       scope.$watch(function() { return controller[attrs.uibAccordionTransclude]; }, function(heading) {
         if (heading) {
-          var elem = angular.element(element[0].querySelector('[uib-accordion-header], [data-uib-accordion-header]'));
+          var elem = angular.element(element[0].querySelector(getHeaderSelectors()));
           elem.html('');
           elem.append(heading);
         }
       });
     }
   };
+
+  function getHeaderSelectors() {
+      return 'uib-accordion-header,' +
+          'data-uib-accordion-header,' +
+          'x-uib-accordion-header,' +
+          'uib\\:accordion-header,' +
+          '[uib-accordion-header],' +
+          '[data-uib-accordion-header],' +
+          '[x-uib-accordion-header]';
+  }
 });