Added the ability to have a polymorphic in a conditions hash

Pretty simple enhancement:

If you have:

class Tagging < ActiveRecord::Base
  belongs_to :taggable, :polymorphic => true

class Post < ActiveRecord::Base
  has_many :taggings, :as => :taggable

You can do:

Tagging.find :all, :conditions => {:taggable => Post.find 1 }

and you will get a find with this sql along the lines of:

SELECT * FROM taggings WHERE taggable_id = 1 AND taggable_type = 'Post'