fix port reporting

This fixes an issue where the found port was not reported properly. The output from the examples now looks like:

```bash
$ node example/portscan.js 
Found a closed port at 3000
{ [Error: connect ECONNREFUSED]
  code: 'ECONNREFUSED',
  errno: 'ECONNREFUSED',
  syscall: 'connect' }
Status at port 3000 is closed
{ [Error: connect ECONNREFUSED]
  code: 'ECONNREFUSED',
  errno: 'ECONNREFUSED',
  syscall: 'connect' }
Status at port 3005 is open
Found an open port at 3005
```

This fixes https://github.com/baalexander/node-portscanner/issues/15