do not load Bootstrap in non-admin controller for non-bundle themes.

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | -
| Refs tickets  | #2041
| License       | MIT
| Doc PR        | -

like so:
```php
$test = function isAdminController(Zikula_View $view) {
    $type = $view->getRequest()->get('type');
    $zkType = $view->getRequest()->attributes->get('_zkType');
    return ($type == 'admin' || $zkType == 'admin');
};

$result = $test('a', 'b', 'c');
```