(#3059) - Can't refresh appcache

Had a cheeky peak at the http-server docs:
https://github.com/nodeapps/http-server#available-options

-c Set cache time (in seconds) for cache-control max-age header, e.g. -c10 for 10 seconds (defaults to '3600'). To disable caching, use -c-1.

Seems to work a treat.