#178358 by kbahey, Views integration for favorite nodes.

- Filter for current users (my favorite nodes)
- Filter for all nodes that have been added to favorites by any user.
- A field that shows how many users have added the node to favorites,
  useful as an indication for popularity.
- An argument that allows filtering of Favorites nodes for a specific user.
  This is useful to show "editor's picks" and such type of lists.