Parse hash bang

If the script has no regular file extension, bugger should check if the file starts with a hash bang (`#!/some/path`), if the first line contains node or coffee, it should work magically. The following scripts as tests:

```
#!/usr/bin/env node
function notValidCoffee() {}
console.log("ok");
process.exit(0);
```

```
#!/usr/bin/env coffee
notValidNode = ->
console.log 'ok'
process.exit 0
```

```
#!/any/path/coffee --some-arg
notValidNode = ->
console.log 'ok'
process.exit 0
```

* To make the magic opt-out bugger should support `--language=coffee` and `--language=node`.
* Support --no-hang (exit bugger when script has finished running) if possible. This could make testing this stuff way easier.