Arguments are not correctly passed to the executed file

Some arguments are passed to the executed file and some are not (and generate errors).

```
$ cat test.js
console.log(process.argv);
$ cover run test.js some arguments
[ 'node', '/tmp/options-test/test.js', 'some', 'arguments' ]
$ cover run test.js --some --arguments
error: unknown option `--some
```

`commander` is intercepting the arguments and exits the program since it doesn't recognize them.
