Rename log file to include site configuration file name.

Author: Pierre Buyle

templates/sites-available/drupal-site.j2

@@ -28,8 +28,8 @@ server {
     limit_conn {{item.limit_conn|default('arbeit 32')}};
 
     ## Access and error logs.
-    access_log {{nginx_drupal_log_path}}/{{item.server_name}}_access.log;
-    error_log {{nginx_drupal_log_path}}/{{item.server_name}}_error.log;
+    access_log {{nginx_drupal_log_path}}/{{item.server_name}}_{{item.file_name}}_access.log;
+    error_log {{nginx_drupal_log_path}}/{{item.server_name}}_{{item.file_name}}_drupal_error.log;
 
     ## See the blacklist.conf file at the parent dir: /etc/nginx.
     ## Deny access based on the User-Agent header.