Enable addition OAuth 2.0 grant flows

Would it be cleaner to do something like:

In CSS:
```css
.required:after {
    content: "*";
}
```

and then

```HTML
<label for="clientSecret" ng-style:"{required: requiresSecret}">
```

and add to the controller:
```javascript
$scope.requiresSecret = credentials.grantType.type !== 'token';
```

and remove the span?