added quoation around avoid_id
added :scope string support
add_to_list_top and add_to_list_bottom, now public
bottom_item now ignores items not_in_list
bug fix.
but fix.
Merge branch 'master' of https://github.com/hideoyanagi/acts_as_list

Conflicts:
	lib/acts_as_list/active_record/acts/list.rb
	lib/acts_as_list/version.rb