git-daemon.pl: second iteration based on feedback from Ian.

git-daemon.pl: second iteration based on feedback from Ian.

Instead of invoking the standard git-daemon via userv, do what
the standard git-daemon does and invoke git-upload-pack.

Log errors to syslog. Obtain the client IP address and port.

Use a configuration file to work out the user from the
virtual host name and tilde part of the URL.
Put the syntax check regexes in the configuration file.

Pass parameters to userv git-upload-pack service with
user-defined variables instead of command line arguments.