migrate to Rails 4.0 (closes foodcoops#214)

Conflicts:
	Gemfile.lock

spec/models/article_spec.rb

@@ -36,12 +36,12 @@ describe Article do
   end
 
   it 'keeps a price history' do
-    expect(article.article_prices.all.map(&:price)).to eq([article.price])
+    expect(article.article_prices.map(&:price)).to eq([article.price])
     oldprice = article.price
     sleep 1 # so that the new price really has a later creation time
     article.price += 1
     article.save!
-    expect(article.article_prices.all.map(&:price)).to eq([article.price, oldprice])
+    expect(article.article_prices.reload.map(&:price)).to eq([article.price, oldprice])
   end
 
   it 'is not in an open order by default' do