PHP ActiveRecord logging via Slim logger.

Adapter which enables logging from [PHP ActiveRecord](http://www.phpactiverecord.org/)  to Slim Logger. Been using this myself for a while.

```php
$app = new \Slim\Slim(array(
  'log.writer' => new \Slim\Extras\Log\DateTimeFileWriter()
));

ActiveRecord\Config::initialize(function($cfg) use ($connections, $app) {
  $cfg->set_connections($connections);
  $cfg->set_logging(true);
  $cfg->set_logger(new \Slim\Extras\Log\ActiveRecordAdapter($app->getLog(), \Slim\Log::DEBUG));
});
```