Added a dynamic configuration dumper.

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | yes
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | ---
| Fixed tickets | ---
| Refs tickets  | #1702
| License       | MIT
| Doc PR        | ---

This is my idea for the dynamic (mailer) configuration problem, which I discussed with @craigh. You would execute the following code in the ModifyConfigHandler:
```php
$transport = \Zikula\Module\MailerModule\Api\AdminApi::$transportTypes[$vars['mailertype']];
$config = array(
    'transport' => $transport,
    'username' => $vars['smtpusername'],
    'password' => $vars['smtppassword'],
    'host' => $vars['smtpserver'],
    'port' => $vars['smtpport'],
    'encryption' => $vars['smtpsecuremethod'],
    'auth_mode' => $vars['smtpauth'] ? 'login' : null,
    'spool' => array('type' => 'memory'),
    'delivery_address' => null,
    'disable_delivery' => false,
);

$configDumper = $this->view->getContainer()->get('zikula.dynamic_config_dumper');
$configDumper->setConfiguartion('swiftmailer', $config);
```
would result in:
```yaml
#This is a dynamically generated configuration file. Do not touch!

swiftmailer:
    transport: smtp
    username: ...
    password: ...
    host: smtp.gmail.com
    port: 465
    encryption: ssl
    auth_mode: login
    spool: { type: memory }
    delivery_address: null
    disable_delivery: false
```
- refs #1702 
- refs https://github.com/craigh/core/compare/swiftmailer