*.jspf now mapped to servlet as jsp
 authentication added to web.xml
 [fix] link correction according to security concerns
 addfood, listfood, editfood moved to WebContent/secret
 [refactor] delivery address and customer removed
 YamlFileFoodRepository introduced
 snakeyaml-1.13.jar added to /lib
 yaml file name added to web.xml as initparameter