Users can like dive sites

https://trello.com/c/cDSm4ctP/33-users-can-like-dive-sites

![likedivesites](https://cloud.githubusercontent.com/assets/8681076/5112943/8fc9ba24-6ff9-11e4-81d4-9419b6e5f7a5.gif)


Chris, pluralizing this changes the path helper to `dive_site_like_index_path` any way to correct that? Leave it singular? What would you recommend?