git-daemon-verify: validate supplied "host=" hostname
By default require a "host=" extra parameter to be sent by git-daemon
clients (Git has done so since v1.4.0, 2006-06-10) that matches the
hostname configured into $Girocco::Config::gitpullurl or is a variant
of localhost.
Various options are available in Girocco/Config.pm to alter this
default behavior.
If $Girocco::Config::gitpullurl has not been set then no "host="
extended arg will be required or matched by default.
Signed-off-by: Kyle J. McKay <mackyle@gmail.com>