prepare to support upstream openwrt lighttpd pkg

put Turris webapp settings in turris-root.conf

x-ref:
  turris/os/packages#474

turris-root.conf

+# These settings augment OpenWrt (upstream) lighttpd default config
+# to support Turris webapps.
+
+# This is part of turris-webapps package and is not meant to be edited.
+# If you need different setup, uninstall this package and create your own config
+
+# Listen on IPv4 "*:80" (default) and on IPv6 "[::]:80"
+$SERVER["socket"] == "*:80"    {  }
+$SERVER["socket"] == "[::]:80" {  }
+
+# Reset values so that lighttpd does not drop privileges
+# and instead runs as the user who started lighttpd (root).
+# LuCI, Foris, reForis require root to manage router configuration.
+server.username  := ""
+server.groupname := ""
+
 # JSON API
 $HTTP["url"] =~ "^/js/apps.json$" {
         alias.url = ( "/js/apps.json" => "/usr/share/turris-webapps/turris-webapps-json-cgi" )