One suggestion here:  This is not very robust to urls coming in in different forms.  Here are a few different possibilities for how a url could come in:

adventures-with-raphael.herokuapp.com
http://adventures-with-raphael.herokuapp.com
adventures-with-raphael.herokuapp.com/
http://adventures-with-raphael.herokuapp.com/

One way to make all of these work is to use the URI module, which looks something like this:
```
u = URI(url)
u.path += "adventures.json"
u.protocol = "http" unless u.protocol
u.to_s
```

In my solution, I use the postrank-uri gem to make this easy.