title: How to implement more than 2 level navigation in com.android.support:leanback-v17
body: <p>In regular android application I can use navigation drawer for navigate between top level views (sections of app)
  What should be used in tv apps?
  I see only possibility for two level of content organizing Categories -> Movies
  But in our app we have several sections (Live channels, On demand Movies, Recorded shows etc) with categories in most of them.
  Is it possible using standard android.support.v17.leanback.app.BrowseFragment and android.support.v17.leanback.app.DetailsFragment?</p>