Incorporated feedback from review

Signed-off-by: Boris Pruessmann <boris@pruessmann.org>

man/Dockerfile.aarch64

@@ -1,16 +1,6 @@
 FROM    aarch64/ubuntu:xenial
 
-# allow replacing httpredir or deb mirror
-ARG     APT_MIRROR=deb.debian.org
-RUN     sed -ri "s/(httpredir|deb).debian.org/$APT_MIRROR/g" /etc/apt/sources.list
-
-RUN     apt-get update && apt-get install -y \
-          git \
-          bash \
-          curl \
-          gcc \
-          gccgo \
-          make
+RUN     apt-get update && apt-get install -y git golang-go curl
 
 ENV     GO_VERSION 1.7.5
 ENV     GOARCH arm64