Use only new hash syntax

db/migrate/20130105115603_create_event_attachments_table.rb

@@ -2,12 +2,12 @@ class CreateEventAttachmentsTable < ActiveRecord::Migration
   def up
     create_table :event_attachments do |t|
       t.references :event
-      t.string :title, :null => false
+      t.string :title, null: false
       t.string :attachment_file_name
       t.string :attachment_content_type
       t.integer :attachment_file_size
       t.datetime :attachment_updated_at
-      t.boolean :public, :default => true
+      t.boolean :public, default: true
       t.timestamps
     end
   end