Update language strings in en.php

Author: Kristan Kenney

web/inc/i18n/en.php

@@ -265,6 +265,7 @@
     'email antivirus'  => 'Anti-Virus',
     'email antispam'  => 'Spam Filter',
     'database server'  => 'Database Server',
+	'backend server' => 'Backend Server',
     'ftp server'  => 'FTP Server',
     'job scheduler'  => 'Task Scheduler',
     'firewall'  => 'Firewall',