Fix definitions reloading

`engine_name` is not available in a `to_prepare` block.

Author: tvdeyen

lib/alchemy/engine.rb

@@ -64,11 +64,11 @@ class Engine < Rails::Engine
 
     config.to_prepare do
       elements_reloader = Rails.application.config.file_watcher.new([ElementDefinition.definitions_file_path]) do
-        Rails.logger.info "[#{engine_name}] Reloading Element Definitions."
+        Rails.logger.info "[alchemy] Reloading Element Definitions."
         ElementDefinition.reset!
       end
       page_layouts_reloader = Rails.application.config.file_watcher.new([PageDefinition.layouts_file_path]) do
-        Rails.logger.info "[#{engine_name}] Reloading Page Layouts."
+        Rails.logger.info "[alchemy] Reloading Page Layouts."
         PageDefinition.reset!
       end
       [elements_reloader, page_layouts_reloader].each do |reloader|