clearly require dependencies

seanlinsley · seanlinsley · commit e5056e67de1d · 2013-12-15T22:36:51.000-06:00
activerecord-hackery/ransack#318
diff --git a/lib/active_admin.rb b/lib/active_admin.rb
@@ -1,4 +1,6 @@
-require 'active_support/core_ext/class/attribute' # needed for Ransack
+require 'active_support/core_ext'
+require 'set'
+
 require 'ransack'
 require 'ransack_ext'
 require 'bourbon'
