Merge pull request #246 from mikz/patch-1

Fix undefined method .path on nil

Author: jonleighton

lib/spring/application.rb

@@ -102,7 +102,7 @@ def preload
       watcher.add loaded_application_features
       watcher.add Spring.gemfile, "#{Spring.gemfile}.lock"
 
-      if defined?(Rails)
+      if defined?(Rails) && Rails.application
         watcher.add Rails.application.paths["config/initializers"]
         watcher.add Rails.application.paths["config/database"]
       end