Also check BLOG_USE_FEATURED_IMAGE in templates when displaying blog post's featured image.
Merge
Added a sort_by template filter for general use.
Removed Slugged.Meta.ordering since it'll generally always be nuked by Meta on a subclass - and added correct ordering to BlogCategory.
Clean up BlogCategory.Meta.
Preserve slugs & URLs when pages are moved.
Remove obsolete reset_slugs().
Check overridden() when changing slug.
In set_parent(), call save() before get_slug().
Make slug changes propagate to all descendant pages.
pep8 fix
Fix bug in Page.set_parent() when no parent set.
Allow passing None to Page.set_parent().
Add tests for Page.get_slug() and Page.get_parent().
Remove debugging print statement.
Fix bug in slug handling when adding a new page.
Move clean_content to new DisplayableAdminForm.
Merge branch 'master' into slug_reset
Fix parent of Team and History pages in fixtures

Assign the Team and History pages to the About page (id 2) instead of the Blog page (id 1) in Page fixtures.
Fix generating descriptions when saving page instances directly, as their content type subclass fields weren't available for the description.