Remove support for specifying the port number using "-H example.com:80".

Remove support for specifying the port number using "-H example.com:80".
Since this didn't work anyway (because ":80" wasn't stripped from the
"host_name" after extracting the "server_port"), nobody can be using
this syntax, and it prevents "-H" from accepting IPv6 addresses
(neufeind - 1865082).  IMO, fixing it to recognize both ":80" and IPv6
addresses isn't worth it, as the ":80" syntax doesn't seem very useful
for Nagios plugins (given the way how they are usually called in Nagios
command definitions).

git-svn-id: https://nagiosplug.svn.sourceforge.net/svnroot/nagiosplug/nagiosplug/trunk@1891 f882894a-f735-0410-b71e-b25c423dba1c