activate/deactivate backup-cronjob with the backup-enabled setting

Signed-off-by: Michael Kaufmann (d00p) <d00p@froxlor.org>
the link to open the customer-traffic details via admin-panel now uses rel='external' as we do with switch-user

Signed-off-by: Michael Kaufmann (d00p) <d00p@froxlor.org>
generalize language string

Signed-off-by: Michael Kaufmann (d00p) <d00p@froxlor.org>
display domains one below the other, so you get a better overview

Signed-off-by: Michael Kaufmann (d00p) <d00p@froxlor.org>