Also move send_credentials() and receive_credentials() to GUnixConnection. This code might change, discussion is still ongoing in https://bugzilla.gnome.org/show_bug.cgi?id=617483.
Things compile and the test-suite passes. Still need to hook up gio.symbols and docs. There are still a bunch of TODOs left in the sources that needs to be addressed. Signed-off-by: David Zeuthen <davidz@redhat.com>
