Divide ActiveRecord::ConnectionAdapters::OracleEnhancedColumnDumper

Divide ActiveRecord::ConnectionAdapters::OracleEnhancedColumnDumper

To prepare merge rails4 branch into master, these modules should be stored in separe file because ActiveRecord::ConnectionAdapters::OracleEnhancedColumnDumper just supports
Rails 4 and does not Rails 3.2 and earlier versions.