Add support for Node.js

Hello, I like Max Ogden's workflow for frontend development with browserify and beefy:
https://gist.github.com/maxogden/5147486

That way you can throw this into a file called index.js:
```javascript
window.Isomer = require('isomer');
```

Then, on the command-line, you can run:
```
beefy index.js:bundle.js --live
```

You can also omit the window and dev without globals, and you have a working livereload and it's really easy to just start developing right away. :smile: 

So... That's why I made this simple way to use gulp to compile something that module.exports Isomer. It's super handy! And maybe it might help with issue #16.