Run as root by default

Optionally run as another user/group only if
the env vars are specified. Should give flexibility
to those who need to run processes as root and open ports
without having to request additional priveleges

docker/docker-compose.ci.yml

@@ -33,6 +33,8 @@ services:
       LE_STAGING: 'true'
       FORCE_COLOR: 1
       DB_SQLITE_FILE: '/data/mydb.sqlite'
+      PUID: 1000
+      PGID: 1000
     volumes:
       - npm_data:/data
     expose: