[#37] Updated the gem
[#37] Upgrade admin dashboard to use new syntax

dashboards.rb -> dashboard.rb
[#37] Updated active_admin initializer to use built in cancan adapter

Removed explicit authorization check in controllers.
[#37] f.buttons deprecated for f.actions (formtastic)
[#37] Update the active_admin named route used in the footer
[#37] Dashboard page has highest priority (first element in nav)
[#37] Fixing the admin stylesheets

* Removed duplicated stylesheet active_admin_custom
* Tabs to spaces, remove trailing whitespace
* Wrap custom changes to admin styles in the admin scope (new feature of
  activeadim 0.6_
[#37] Fix the JS function which hides the 'articles' admin page
[#37] Remove unused JS function from active_admin.js

Looks like this maybe used to be responsible for moving between guide
steps on the main site, but it isn't doing anything currently.
[#37] Fix admin dashboard permissions (useless use of proc)