connections.cgi: Fix Expires time Heading in Connections cgi page

- The Expires time heading for the Connections WUI page has seconds listed. However the
   code is converting the seconds to hours:minutes:seconds.
- This patch is changing the heading to H:M:S in English and the equivalent in the other
   languages. I have basewd this on the initial letter for Hours, Minutes & Seconds in
   each of the languages.

Signed-off-by: Adolf Belka <adolf.belka@ipfire.org>
Reviewed-by: Peter Müller <peter.mueller@ipfire.org>

langs/nl/cgi-bin/nl.pl

@@ -1201,6 +1201,7 @@
 'hour-graph' => 'Uur',
 'hours' => 'uren',
 'hours2' => 'Uren',
+'hours:minutes:seconds' => 'U:M:S',
 'icmp selected but no type' => 'ICMP als protocol geselecteerd, maar er is geen ICMP type gespecificeerd.',
 'icmp type' => 'ICMP Type',
 'id' => 'ID',
@@ -1877,7 +1878,6 @@
 'secondary dns' => 'Secondaire DNS:',
 'secondary ntp server' => 'Secondaire NTP server',
 'secondary wins server address' => 'Secondaire WINS serveradres',
-'seconds' => 'Sec.',
 'section' => 'Sectie',
 'secure shell server' => 'Secure Shell Server',
 'security' => 'Beveiliging',