wrong global --bundle/--dab input

``` console
$ kompose --bundle docker-voting-bundle.dsb convert
FATA[0000] Error: 'compose' file and 'dab' file cannot be specified at the same time
```

Figured out `opt.InputFile` received `docker-voting-bundle.dsb` instead of `docker-compose.yml` then the [if clause](https://github.com/ngtuna/kompose/blob/master/cli/app/app.go#L74) returned true.
