Allow user's to see their own favorites

[bloudermilk]

As a stepping stone to #283, we can create a page like /account/favorites that allows an authenticated user to view their own favorites. It will allow us to test #280 and provide incremental value on top of our MVP favorites functionality.

The UI can be roughly based on the the Lists design, though using our existing components.

• The title would just be something like "Your Favorites"
• The list items would use the existing OrganizationCard design
• Everything else in the mock can be left out (karma, profile info, description, discussions, "also in...")