acme: add support for nginx webserver

This adds a metapakcge for acme luci ap without uhttpd dependency and adds entities and check to stop handle nginx server and modify the certificate set automatically.

Signed-off-by: Ansuel Smith <ansuelsmth@gmail.com>

net/acme/files/acme.config

@@ -8,5 +8,6 @@ config cert 'example'
        option use_staging 1
        option keylength 2048
        option update_uhttpd 1
+       option update_nginx 1
        option webroot ""
        list domains example.org