Statistics module patch by Jeremy:

  - removed custom user-page configuration
  - added user-page configuration as group into statistics_settings()
  - inlined logic to display user-page within statistics_page()
  - changed references of "top content" to "most popular content"
  - updated help to reflect recent changes
  - removed references to title/subtitle text configuration
  - properly load _settings data for popular content block
  - fix admin pages to display referrers and top nodes (don't return...)