[1.2.X] Fixed a suite of errors in the ORM -- a) fixed calling...

[1.2.X] Fixed a suite of errors in the ORM -- a) fixed calling values_list().values_list() and changing whether the results are flat, b) fixed an issue with fields on the left-hand side of what becomes the HAVING clause not being included in the GROUP BY clause, and c) fixed a bug with fields from values() calls not being included in the GROUP BY clause.  This fixed the recent test failures under postgresql. Backport of [14715].

git-svn-id: http://code.djangoproject.com/svn/django/branches/releases/1.2.X@14716 bcc190cf-cafb-0310-a4f2-bffc1f526a37