[Dockerfile] Use LABEL instead of deprecated MAINTAINER command
diff --git a/Dockerfile b/Dockerfile
index 79cb15b..314285e 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -9,7 +9,7 @@
# Use Ubuntu Trusty Tahr as base image as we're using on Travis CI
# I also tested with Ubuntu 16.04, should be good with it!
From ubuntu:14.04
-MAINTAINER Peter Dave Hello <hsu@peterdavehello.org>
+LABEL maintainer="Peter Dave Hello <hsu@peterdavehello.org>"
# Prevent dialog during apt install
ENV DEBIAN_FRONTEND noninteractive