Merge pull request #9745 from cglewis/master

MAINTAINER is deprecated, now using LABEL

docker/blocks/graphite1/Dockerfile

 FROM phusion/baseimage:0.9.22
-MAINTAINER Denys Zhdanov <denis.zhdanov@gmail.com>
+LABEL maintainer="Denys Zhdanov <denis.zhdanov@gmail.com>"
 
 RUN apt-get -y update \
   && apt-get -y upgrade \

docker/blocks/openldap/Dockerfile

 FROM debian:jessie
 
-MAINTAINER Christian Luginbühl <dinke@pimprecords.com>
+LABEL maintainer="Christian Luginbühl <dinke@pimprecords.com>"
 
 ENV OPENLDAP_VERSION 2.4.40
 

docker/blocks/smtp/Dockerfile

 FROM centos:centos7
-MAINTAINER Przemyslaw Ozgo <linux@ozgo.info>
+LABEL maintainer="Przemyslaw Ozgo <linux@ozgo.info>"
 
 RUN \
     yum update -y && \