model changes for two layer brand concept
creating BrandGroups and BrandUses for all existing Brands
oi-related changes for BrandGroups and BrandUses
speed up active_issue query for brand_groups
display related changes for BrandGroups and BrandUses
some changes for issue_counts
add publisher's age guidelines/ratings field
changes found during migration test on beta
add search for brand_groups, display brand image in separate column on list pages
Merge branch 'brand' of github.com:GrandComicsDatabase/gcd-django into devel