add article info url to articles and suppliers
do not use attr_accessible (yet) - mass assignment errors occur
do not show link when it is blank
show article info url on show group_order too
cleanup article info icon generation
include article info link in other screens as well
Merge branch 'article-info-url' into foodcoop-adam-new

Conflicts:
	app/helpers/group_orders_helper.rb
	app/views/group_orders/_form.html.haml
	app/views/group_orders/show.html.haml
	db/schema.rb