added ability to use sort order in CSV
refactor ActiveAdmin.flash
make ActiveAdmin.flash’s closable
close after attr for js flash messages
Allow CSV export without column name
Document column_names paramters for csv
Simplify code
some styling for input[type=button] as for input[type=submit]
some styling for button as for input[type=submit]
fix title of pages with active_admin_logged_out layout (fix #3428)
remove formtastic locale keys
use formtastic_i18n gem
Fix faulty placeholder in has many forms.

2133d7cdf6ec9d85406a95af9a6496306ef6492e introduced an error in all has_many forms with namespaced models.
Because ids cannot contain a forward-slash it will be rewritten by rails helpers to an underscore. So the javascript could not replace the placeholders anymore.
Added a test to capture future breaks
use same item dsl for actions and actions with dropdown (fix #2625)
join IndexAsTable default actions
extend documentation for new index actions style
fix feature for devise text change
Documented the `:optional` option for belongs_to

I found the `:optional` option very useful for a project to expose nested resources in the global menu ; here's a short proposal to expose it in the documentation.

Thanks for all the good work in activeadmin, you rock!
name cancan and cancancan in docs