Developer credits

Git commits in Moodle 2.0.6 by Sun Zhigang

commit 94eaa78a25b83896037540fa228cf94789f0f7f5
Author: Sun Zhigang <sunner@gmail.com>
Date:   Tue, 11 Oct 2011 09:21:23 +0800
Tag:    v2.0.6

MDL-29722 - No default guest enrol instance for requested courses

commit e293df9442e0a40374dcd8e4fc3ba91b7e4cbab5
Author: Sun Zhigang <sunner@gmail.com>
Date:   Tue, 04 Oct 2011 19:50:30 +0800
Tag:    v2.0.6

MDL-29656 Fix bad string reference

commit ff6c9d2f86c891d0865890dfca41a60a1764ab1d
Author: Sun Zhigang <sunner@gmail.com>
Date:   Wed, 31 Aug 2011 16:36:31 +0800
Tag:    v2.0.6

MDL-29191 - Show creator's fullname instead of username