[1.2.X] Fixed #15253 -- Added 1.1.3 release notes, and added sections to the...

[1.2.X] Fixed #15253 -- Added 1.1.3 release notes, and added sections to the 1.2.4 and 1.3 release notes about the December security announcement.

Backport of r15485 from trunk.

git-svn-id: http://code.djangoproject.com/svn/django/branches/releases/1.2.X@15486 bcc190cf-cafb-0310-a4f2-bffc1f526a37