fix(alert): update template to Bootstrap 3

Author: pkozlowski-opensource

src/alert/docs/demo.js

@@ -1,6 +1,6 @@
 function AlertDemoCtrl($scope) {
   $scope.alerts = [
-    { type: 'error', msg: 'Oh snap! Change a few things up and try submitting again.' }, 
+    { type: 'danger', msg: 'Oh snap! Change a few things up and try submitting again.' },
     { type: 'success', msg: 'Well done! You successfully read this important alert message.' }
   ];
 

template/alert/alert.html

@@ -1,4 +1,4 @@
-<div class='alert' ng-class='type && "alert-" + type'>
+<div class='alert' ng-class='"alert-" + (type || "warning")'>
     <button ng-show='closeable' type='button' class='close' ng-click='close()'>&times;</button>
     <div ng-transclude></div>
 </div>