Merge branch '3503-german' into 'develop'

German E-Mail Konto vs mailbox #3503

Closes #3503

See merge request ispconfig/ispconfig3!1200

Author: Till Brehm

interface/web/dashboard/lib/lang/de_dashlet_mailquota.lng

@@ -1,5 +1,5 @@
 <?php
-$wb['mailquota_txt'] = 'Mailbox-Speicherplatz';
+$wb['mailquota_txt'] = 'E-Mail-Speicherplatz';
 $wb['email_txt'] = 'E-Mail-Adresse';
 $wb['name_txt'] = 'Name';
 $wb['used_txt'] = 'Verwendet';