.fresh config run_args incompatible with space-separated args passed with Go's flag.Func

example:
```
flag.Func("trusted origins", "Trusted CORS origins",
		func(val string) error {
			trustedOrigins = strings.Fields(val)
			return nil
		})
```

and in my `.fresh.yaml`:
```
run_args: "--cors-trusted-origins http://localhost:9000 http://localhost:9001"
```

But only the first arg is received.