Add log level config value to stderr channel (laravel#5558)

Author: jnoordsij

config/logging.php

@@ -74,6 +74,7 @@
 
         'stderr' => [
             'driver' => 'monolog',
+            'level' => env('LOG_LEVEL', 'debug'),
             'handler' => StreamHandler::class,
             'formatter' => env('LOG_STDERR_FORMATTER'),
             'with' => [