Allow docs-hero class to be customizable (#329)

* Allow docs-hero class to be customizable

* add class property on docs-hero component

* add class customization on demo 2 docs-hero

Author: miguelcobain

addon/components/docs-hero/component.js

@@ -44,5 +44,13 @@ export default Component.extend({
     @argument byline
     @type String
   */
-  byline: projectDescription
+  byline: projectDescription,
+
+  /**
+    Class to add to the wrapper element
+
+    @argument class
+    @type String
+  */
+  class: null
 });

addon/components/docs-hero/template.hbs

@@ -1,6 +1,7 @@
 <div class='
   docs-bg-brand docs-text-white
   docs-px-4 docs-py-16 docs-text-center
+  {{class}}
 '>
   <div class="docs-max-w-sm docs-mx-auto">
     <h1 class='

tests/dummy/app/pods/docs/components/docs-hero/demo-2/template.hbs

@@ -4,6 +4,7 @@
       prefix='EmberData'
       heading='Something'
       byline='The best addon ever. Now playing in theaters.'
+      class='some-custom-class'
     }}
   {{/demo.example}}