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
remove formtastic locale keys
use formtastic_i18n gem
helper_method env
for example to access user agent from arbre views
add unsupported browser panel
style unsupported browser panel (close #2678)
add de and de-CH locales for unsupported browsers
fix tests
specs for UnsupportedBrowser
cosmetics and typos
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
Merge pull request #3421 from timoschilling/supported_browsers

warn: supported browser
fix feature for devise text change
name cancan and cancancan in docs