add sysvinit integration for git-daemon

Here's a patch which I've applied on my local git packages and which
I'm using successfully since some time on my own servers.

I've tried to do it as unintrusively as possible to integrate it with
the style of the rest of the package.  The init script is as minimally
as possible different from the initscript template from dh-make, so
I'm pretty sure it's correct.

[jn: rebased, with new change description summarizing the bug log]

Fixes: http://bugs.debian.org/422139
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
diff --git a/debian/git-daemon/default b/debian/git-daemon/default
new file mode 100644
index 0000000..2020805
--- /dev/null
+++ b/debian/git-daemon/default
@@ -0,0 +1,14 @@
+# Defaults for git-daemon initscript
+# sourced by /etc/init.d/git-daemon
+# installed at /etc/default/git-daemon by the maintainer scripts
+
+#
+# This is a POSIX shell fragment
+#
+
+GIT_DAEMON_ENABLE=false
+GIT_DAEMON_USER=gitdaemon
+GIT_DAEMON_DIRECTORY=/var/cache/git
+
+# Additional options that are passed to the Daemon.
+GIT_DAEMON_OPTIONS=""