Remove timestamps from DB

Timestamps are now marked as non-null, causing problems all over, so I'd
rather remove them.

Author: Pluies

db/migrate/20111002143044_create_countries.rb

@@ -4,8 +4,6 @@ def change
       t.string :name
       t.string :center
       t.text :polygons
-
-      t.timestamps
     end
   end
 end