Include version const (activerecord-hackery#1477)

Include the file `version.rb` to define the `Ransack::VERSION` const.

Ransack defines a `VERSION` const, but the `version.rb` file is not included in the requires list in the gem entry code.

Author: ozydingo

lib/ransack.rb

@@ -21,6 +21,7 @@ class UntraversableAssociationError < StandardError; end
 require 'ransack/translate'
 require 'ransack/active_record'
 require 'ransack/context'
+require 'ransack/version'
 
 ActiveSupport.on_load(:action_controller) do
   require 'ransack/helpers'