timestamps gives a created_at field not created_on.

[#3093 state:committed]

Signed-off-by: Jeremy Kemper <jeremy@bitsweat.net>

activerecord/examples/performance.rb

@@ -75,13 +75,13 @@ else
   puts 'Inserting 10,000 users and exhibits...'
   10_000.times do
     user = User.create(
-      :created_on => today,
+      :created_at => today,
       :name       => Faker::Name.name,
       :email      => Faker::Internet.email
     )
 
     Exhibit.create(
-      :created_on => today,
+      :created_at => today,
       :name       => Faker::Company.name,
       :user       => user,
       :notes      => notes