Made directive/spinner.js match code style

Added use strict.
Removed unused `attrs` var;

h/static/scripts/directive/spinner.js

-module.exports = ['$animate', function ($animate) {
+module.exports = ['$animate', function($animate) {
+  'use strict';
   return {
-    link: function (scope, elem, attrs) {
+    link: function(scope, elem) {
       // ngAnimate conflicts with the spinners own CSS
       $animate.enabled(false, elem);
     },
     restrict: 'C',
     template: '<span><span></span></span>'
-  }
+  };
 }];