Detect in script if io.js or node is running

I would absolutely adore the ability to check whether Node or io.js is running the script. Perhaps via changing

``` javascript
process.versions.node
```

to

``` javascript
process.versions.iojs
```

As it is, the best way seems to be to have the script fork a child_process of the executable that started it, with the `-h` flag, then to parse for `iojs.org`
