added healthcheck

config/routes.rb

@@ -1,5 +1,6 @@
 if Redmine::Plugin.installed? :baupm_core
   RedmineApp::Application.routes.draw do
     get '/manifest.json', :controller => 'manifest', :action => 'index', :as => 'manifest_json'
+    get '/_healthcheck', :controller => 'healthcheck', :action => 'index', :as => 'healthcheck'
   end
 end