Users can mark map to create site and view sites

https://trello.com/c/iVd5bW9y/25-add-locations-to-map

![adddivesites](https://cloud.githubusercontent.com/assets/8681076/5172429/c1a386d6-73ed-11e4-8438-0773cfc6ef77.gif)

I'd replace the `alert()` with console.warn, or a warning on the page