Remove Link to Blog in QE + Refactor quayRequire Directive (#2523)

* refactoring quayRequire directive

* added tests, show element if input changes

* use ngIfDirective in QuayRequireDirective

static/js/directives/quay-layout.js

@@ -2,20 +2,6 @@
  * Directives which show, hide, include or otherwise mutate the DOM based on Features and Config.
  */
 
-/**
- * Adds a quay-require attribute includes an element in the DOM iff the features specified are true.
- */
-angular.module('quay').directive('quayRequire', function ($animate, Features, AngularHelper) {
-  return {
-    transclude: 'element',
-    priority: 600,
-    terminal: true,
-    restrict: 'A',
-    link: AngularHelper.buildConditionalLinker($animate, 'quayRequire', function(value) {
-      return Features.matchesFeatures(value);
-    })
-  };
-});
 
 /**
  * Adds a quay-show attribute that shows the element only if the attribute evaluates to true.