Spree::BannerBox.enabled accepts multiple categories

Conflicts:
	app/models/spree/banner_box.rb
Attachment style names fix

Conflicts:
	app/models/spree/app_configuration_decorator.rb
Search filter for admin banner index

Conflicts:
	app/models/spree/banner_box.rb
Fix new banner button in edit page
Rename presentation to alt_text; helper refactor
DRYed up banner forms
Spree 1.3 tweaks