added ability to use sort order in CSV
fix title of pages with active_admin_logged_out layout (fix #3428)
use same item dsl for actions and actions with dropdown (fix #2625)
join IndexAsTable default actions
extend documentation for new index actions style
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!
remove i18n key `active_admin.update_model`

This key is not used by active admin, see #3172
remove i18n key `active_admin.create_model`
don't configure authentication_method if devise isn't used (fix #3467)
on table index column block add sortable column by default
add #3075 to changelog
rename locale iso 'no-NB' to 'nb'

see https://en.wikipedia.org/wiki/ISO_639:nb for details
sort by default only by table column names

do not sort by associations or virtual attributes
Merge pull request #3075 from dmitry/table_sortable_default_true

Column block on table index should be sortable by default
Use the latest release of yard
Merge pull request #3522 from strivedi183/bump-yard

Use the yard 0.8.7.6 or greater
pimp the changelog

just run `pimpmychangelog`
add locale key active_admin.devise.links.sign_up
remove es.active_admin.blank_slate.entry

this don't exist in 'en' and is not used by ActiveAdmin
mv locale key fr.active_admin.access_denied

mv locale key fr.active_admin.access_denied to fr.active_admin.access_denied.message

see:
https://github.com/activeadmin/activeadmin/blob/master/lib/active_admin/error.rb#L15