Merge pull request activeadmin#71 from daniel-g/master

Do not split the sort

Author: elia

lib/active_admin/mongoid/document.rb

@@ -115,8 +115,7 @@ def columns_hash
 
     def reorder sorting
       return unscoped if sorting.blank?
-      options = sorting.split(/ |\./)
-      options.shift if options.count == 3
+      options = sorting.split(' ')
       field, order = *options
       unscoped.order_by(field => order)
     end