Remove :rails_root/public/system from default URL of S3 storage

So instead of having:

    http://s3.amazonaws.com/paperclip/var/www/foo.com/current/avatars/1/original/foo.jpg

because default path has the :rails_root, now you'd have:

    http://s3.amazonaws.com/paperclip/avatars/1/original/foo.jpg

This shouldn't affect your application because you'd normally set the path to some string.

lib/paperclip/storage/s3.rb

@@ -86,7 +86,7 @@ def self.extended base
           @s3_headers     = @options.s3_headers     || {}
 
           unless @options.url.to_s.match(/^:s3.*url$/) || @options.url == ":asset_host"
-            @options.path         = @options.path.gsub(/:url/, @options.url)
+            @options.path         = @options.path.gsub(/:url/, @options.url).gsub(/^:rails_root\/public\/system/, '')
             @options.url          = ":s3_path_url"
           end
           @options.url = @options.url.inspect if @options.url.is_a?(Symbol)