Dependency on bourbon not listed

Created by: pedantic-git

After upgrading to administrate 0.2.2 (from 0.2.0) my app started throwing:

File to import not found or unreadable: bourbon.
[snip]
./app/views/layouts/application.html.haml:8:in `_app_views_layouts_application_html_haml___2930206960703904785_47038691733580'

This was fixed by adding the 'bourbon' gem to my Gemfile, but I feel it should properly be included in administrate's dependencies instead.