Add an ':association_options' option for passing additional options to the association creation methods.

Signed-off-by: rick <technoweenie@gmail.com>

README

@@ -50,6 +50,7 @@ has_attachment(options = {})
     :processor        # Sets the image processor to use for resizing of the attached image.
                       # Options include ImageScience, Rmagick, and MiniMagick.  Default is whatever is installed.
     :uuid_primary_key # If your model's primary key is a 128-bit UUID in hexadecimal format, then set this to true.
+    :association_options  # attachment_fu automatically defines associations with thumbnails with has_many and belongs_to. If there are any additional options that you want to pass to these methods, then specify them here.
     
 
   Examples:

lib/technoweenie/attachment_fu.rb

@@ -103,7 +103,11 @@ module Technoweenie # :nodoc:
         end
         attachment_options[:path_prefix]   = attachment_options[:path_prefix][1..-1] if options[:path_prefix].first == '/'
 
-        with_options :foreign_key => 'parent_id' do |m|
+        association_options = { :foreign_key => 'parent_id' }
+        if attachment_options[:association_options]
+          association_options.merge!(attachment_options[:association_options])
+        end
+        with_options(association_options) do |m|
           m.has_many   :thumbnails, :class_name => "::#{attachment_options[:thumbnail_class]}"
           m.belongs_to :parent, :class_name => "::#{base_class}" unless options[:thumbnails].empty?
         end