Fix: setting 0 for fileCache maxAge doesn't work properly. async-cache module's bug or behavior.
Enh: added Handlebars extension to the baseConf.
Enh: added a Handlebars enabled templates async-cache to fileCache.
Enh: in Dev environment, don't cache static assets by default.
Fix: when port is 80, no need to add it to the URL.
Doc: updated docs.