Checking that the config DSL can set the logger, since old versions o…

…f it cannot and Rails plugin loading is cranky

lib/hoptoad_notifier/rails_initializer.rb

@@ -9,7 +9,7 @@ def self.initialize
                      end
 
       HoptoadNotifier.configure(true) do |config|
-        config.logger = rails_logger
+        config.logger = rails_logger if config.respond_to? :logger
       end
     end
   end