unique with scope broken about composite_primary_keys

[djberg96]

This patch fixes it. Copied from the current AR code:

>diff -u uniqueness.orig uniqueness.rb
--- uniqueness.orig 2010-12-01 10:22:15.172986009 -0700
+++ uniqueness.rb   2010-12-01 10:24:00.768986805 -0700
@@ -31,7 +31,7 @@
         end
 
         if relation.exists?
-          record.errors.add(attribute, :taken, :default => options[:message], :value => value)
+          record.errors.add(attribute, :taken, options.except(:case_sensitive, :scope).merge(:value => value))
         end
       end
     end

[cfis]

Thanks Daniel. Change committed (well, I resynced with the new active record version of this method and reapplied the cpk changes).