Automated image builds for registry

By using CI, builds can be scheduled and the process is unambiguous.

Fixes #2 (closed)

Incidentally, fixed #3 (closed) as part of overall cleanup.

golang/latest/Dockerfile

 # Base image: https://hub.docker.com/_/golang/
 FROM golang:latest
-MAINTAINER ethitter
+
+LABEL maintainer="ethitter"
+LABEL version="1.0"
 
 # Install golint
 ENV GOPATH /go
@@ -8,9 +10,11 @@ ENV PATH ${GOPATH}/bin:$PATH
 RUN go get -u github.com/golang/lint/golint
 
 # Add apt key for LLVM repository
+SHELL ["/bin/bash", "-o", "pipefail", "-c"]
 RUN wget -O - https://apt.llvm.org/llvm-snapshot.gpg.key | apt-key add -
 
 # Add LLVM apt repository
+SHELL ["/bin/bash", "-o", "pipefail", "-c"]
 RUN echo "deb http://apt.llvm.org/stretch/ llvm-toolchain-stretch-5.0 main" | tee -a /etc/apt/sources.list
 
 # Install clang from LLVM repository
@@ -21,4 +25,5 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
 
 # Set Clang as default CC
 ENV set_clang /etc/profile.d/set-clang-cc.sh
+SHELL ["/bin/bash", "-o", "pipefail", "-c"]
 RUN echo "export CC=clang-5.0" | tee -a ${set_clang} && chmod a+x ${set_clang}