Add password directive

maybe instead of an array it should be something like
```javascript
var rules = {
  'dcmPAsswordNumber': {rule: /\d/, min: 8, max: 11 }
}
```
that would make overriding it easier, and you could pass the config options as an attribute of the directive like:
```javascript
scope: {
  options: '=dcmPassword'
}```