Bump formastic to ~> 3.0
don't use !important in SVG color mixin

Previously you had to do this to use your own color:

```ruby
ActiveAdmin::Iconic.icon(:check, color: '#8daa92 !important')
```

Now you can drop the !important
Merge pull request #3432 from strivedi183/update_formastic

Bump formastic to ~> 3.0
remove old rake task
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
align all SVG strings
remove unnecessary spaces in SVG strings
remove version and xmlns attars from SVG icons

they only seem to be necessary when embedding in an XML document, and
we only deal with HTML
Fix ES translations for key 'add_new_association'
Merge pull request #3459 from epdp/fix_es_translation_for_has_many_new

Fix ES translations for key 'add_new_association'
at least align the SVGs missing an ID

not sure if the ID should actually be added :-/
Merge pull request #3421 from timoschilling/supported_browsers

warn: supported browser
name cancan and cancancan in docs
Merge pull request #3480 from timoschilling/cancan_docu

name cancan and cancancan in docs