rails runner supports URL as argument

I think it would be convenient if the rails runner supports a URL as argument.

```bash
rails runner https://gist.github.com/voke/56303a30dc0c9faadd8f/raw
```
Any ideas how I can test this? Since the test should go through the bin script ([like this](https://github.com/voke/rails/blob/master/railties/test/application/runner_test.rb#L44)) I must stub the HTTP request in the target app?