move supervisord call into wrapper script

docker/paperless_cmd.sh

@@ -0,0 +1,15 @@
+#!/usr/bin/env bash
+
+rootless_args=()
+if [ $(id -u) == $(id -u paperless) ]; then
+	rootless_args=(
+		--user
+		paperless
+		--logfile
+		supervisord.log
+		--pidfile
+		supervisord.pid
+	)
+fi
+
+/usr/local/bin/supervisord -c /etc/supervisord.conf ${rootless_args[@]}