Specifying scaffold filename format

When running:

```
ruhoh posts new "Hello World"
```

I'd like the generated file to have the following filename:

```
2014-04-hello-world.md
```

instead of:

```
hello-world.md
```

I have tried to pre-define the `filename` variable through the `_scaffold.html` file's front-matter and through the `config.yml`, without success. Is this possible or on the roadmap?

Thanks!
