Ruby 1.8 #instance_methods returns a list of strings, where as 1.9 is…

… symbols. Moved the conditional into class for symmetry with the above Hash#deep_merge

lib/declarative_authorization/rails_legacy.rb

@@ -13,8 +13,8 @@ def deep_merge(other_hash)
   end
 end
 
-unless String.instance_methods.include?('html_safe')
-  class String
+class String
+  unless "".respond_to?(:html_safe)
     def html_safe
       self
     end