Replace Adorable Avatar API (#74)

This commit replaces the API used to generate an Adorable Avatar due to the original one been shut down by its creator. 

See itsthatguy/avatars-api-middleware#108

addon/components/adorable/index.js

@@ -19,7 +19,7 @@ class AdorableAvatarComponent extends ImageAvatarComponent {
   }
 
   _adorableSrc(email, size) {
-    return `https://api.adorable.io/avatars/${size}/${email}`;
+    return `https://api.hello-avatar.com/adorables/${size}/${email}`;
   }
 }