Honors parameters quoting

Before this fix:

```
$ ./objc-run examples/print-args.m "a b"                                                                                                                  ~/objc-run  master@129ea13
argv[0]: examples/print-args
argv[1]: a
argv[2]: b
```

After this fix:

```
$ ./objc-run examples/print-args.m "a b"                                                                                                                ~/objc-run  master@129ea13 ✗
argv[0]: examples/print-args
argv[1]: a b
```