make project overview query postgres compliant

Patch applies cleanly and appears to work fine with MySQL.

The only thing is that it's not clear to me how this patch makes the query pgsql compliant. My best guess is that n.sticky is one of the fields in the ORDER BY statement in project_project_sort_methods() and pgsql gives an error because that isn't one of the fields that is actually returned by the query because it's not in the SELECT statement?

If that's the case then I would say go with it. If not, it might be helpful to write a quick note here as to why this change makes the query pgsql compliant, in case someone looks back at this issue in the future for guidance or for an explanation.