Stream commands incorrect keys parsing

Command *xreadgroup*:

in index.js should be added:

```javascript
case 'xreadgroup':
        for (i = 0; i < args.length - 1; i++) {
          if (args[i].toUpperCase() === 'STREAMS') {
            for (var j = i + 1; j < (args.length - 1); j++) {
              keys.push(j)
            }
            break
          }
        }
      break
```