add docker-entrypoint.sh for redis container

.gitignore

 .DS_Store
 .DS_Store
 node_nodules
 node_nodules
+.make-function

redis/.gitignore

+.make-function

redis/docker-entrypoint.sh

+#!/bin/sh
+set -e
+
+# first arg is `-f` or `--some-option`
+# or first arg is `something.conf`
+if [ "${1#-}" != "$1" ] || [ "${1%.conf}" != "$1" ]; then
+	set -- redis-server "$@"
+fi
+
+# allow the container to be started with `--user`
+if [ "$1" = 'redis-server' -a "$(id -u)" = '0' ]; then
+	find . \! -user redis -exec chown redis '{}' +
+	exec gosu redis "$0" "$@"
+fi
+
+exec "$@"