title: What is scope of class annotated with @Singleton in Mortar
body: <p>How does Mortar handle classes annotated with <code>@Singleton</code>? To clarify, when I use Dagger and have an <code>Activity</code> graph plus'd into the <code>Application</code> graph on every activity create, I also get an activity scoped singleton of any class that is annotated with <code>@Singleton</code> that do not have a provides method in any module.  </p>
  
  <p>If I instead start using Mortar and defining a <code>MortarScope</code> for each screen, is there a way I can scope things to a screen without explicitly having to create a provides for them?  My reason for not wanting to include a <code>Provides</code> is to be able to inject other objects into my activity helper instances without having to manually set fields from the constructor.  </p>