Asset precompile broken (need group: :all)

I get this error:

    ActionView::Template::Error (rails_admin/rails_admin_nestable.css isn't precompiled):
         5:         = nested_tree_nodes @tree_nodes
         6: 
         7: 
         8: = stylesheet_link_tag 'rails_admin/rails_admin_nestable'
         9: = javascript_include_tag 'rails_admin/jquery.nestable'
         10: = javascript_include_tag 'rails_admin/rails_admin_nestable'
       vendor/bundle/ruby/2.0.0/gems/actionpack-3.2.13/lib/sprockets/helpers/rails_helper.rb:142:in `digest_for'
       vendor/bundle/ruby/2.0.0/gems/actionpack-3.2.13/lib/sprockets/helpers/rails_helper.rb:151:in `rewrite_asset_path'
       vendor/bundle/ruby/2.0.0/gems/actionpack-3.2.13/lib/action_view/asset_paths.rb:27:in `compute_public_path'
       vendor/bundle/ruby/2.0.0/gems/actionpack-3.2.13/lib/sprockets/helpers/rails_helper.rb:56:in `asset_path'
       vendor/bundle/ruby/2.0.0/gems/actionpack-3.2.13/lib/sprockets/helpers/rails_helper.rb:49:in `block in stylesheet_link_tag'
       vendor/bundle/ruby/2.0.0/gems/actionpack-3.2.13/lib/sprockets/helpers/rails_helper.rb:43:in `collect'
       vendor/bundle/ruby/2.0.0/gems/actionpack-3.2.13/lib/sprockets/helpers/rails_helper.rb:43:in `stylesheet_link_tag'
       vendor/bundle/ruby/2.0.0/gems/rails_admin_nestable-0.1.4/app/views/rails_admin/main/nestable.html.haml:8:in `_vendor_bundle_ruby_______gems_rails_admin_nestable_______app_views_rails_admin_main_nestable_html_haml__4520128846218037385_69959166418540'
    .......
    .......

RailsAdmin includes a `group: :assets` entry in the initializer block to handle this. https://github.com/sferik/rails_admin/blob/master/lib/rails_admin/engine.rb#L19

This used to be there in RailsAdminNestable, but was taken out: https://github.com/dalpo/rails_admin_nestable/commit/7997179325eed7805980d88fd4643618f09c6277#L1L4

This pull request adds it back in.