Git commits in Moodle 2.5.1 by Ruslan Kabalin

commit e2d5b6cbc822f2f0d826086567304c5fcd385a43
Author: Ruslan Kabalin <r.kabalin@lancaster.ac.uk>
Date:   Mon, 20 May 2013 21:08:34 +0800
Tag:    v2.5.1

MDL-39760: mod_assign: Add few more callback methods.

commit 666117e830c7fac181daf21c538495a84a1787a9
Author: Ruslan Kabalin <r.kabalin@lancaster.ac.uk>
Date:   Fri, 17 May 2013 22:47:50 +0800
Tag:    v2.5.1

MDL-39761: mod_assign: Always check submission plugin status and visibility.

commit eede0dbd7b39d92b4f50527f5070a524553b1424
Author: Ruslan Kabalin <r.kabalin@lancaster.ac.uk>
Date:   Fri, 01 Feb 2013 19:41:08 +0800
Tag:    v2.5.1

MDL-33546: course: Fix current week hightlighting after dragging the section