convert Settings module to Routes. refs #1788. requires route reload.

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | yes
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | -
| Refs tickets  | #1788
| License       | MIT
| Doc PR        | -
I think the solution is to change the `if` above from
```php
if (isset($deleteLangUrl)) {
// reset language settings
SessionUtil::delVar('language');
$url = preg_replace('#(.*)(&lang=[a-z-]{2,5})(.*)#i', '$1$3', $url);
}
```
to 
```php
if (isset($deleteLangUrl)) {
// reset language settings
SessionUtil::delVar('language');
$url = $this->get('router')->generate('zikulasettingsmodule_admin_multilingual', array('_locale' => \System::getVar('language_i18n')), RouterInterface::ABSOLUTE_URL);
}
```
This should generate an url with the default locale.