containers/docker: nuke per the 1.8.0 deprecation note

containers/docker/develop-alpine/Dockerfile

-FROM alpine:3.7
-
-RUN \
-  apk add --update go git make gcc musl-dev linux-headers ca-certificates && \
-  git clone --depth 1 https://github.com/ethereum/go-ethereum && \
-  (cd go-ethereum && make geth) && \
-  cp go-ethereum/build/bin/geth /geth && \
-  apk del go git make gcc musl-dev linux-headers && \
-  rm -rf /go-ethereum && rm -rf /var/cache/apk/*
-
-EXPOSE 8545
-EXPOSE 30303
-
-ENTRYPOINT ["/geth"]

containers/docker/develop-ubuntu/Dockerfile

-FROM ubuntu:xenial
-
-ENV PATH=/usr/lib/go-1.9/bin:$PATH
-
-RUN \
-  apt-get update && apt-get upgrade -q -y && \
-  apt-get install -y --no-install-recommends golang-1.9 git make gcc libc-dev ca-certificates && \
-  git clone --depth 1 https://github.com/ethereum/go-ethereum && \
-  (cd go-ethereum && make geth) && \
-  cp go-ethereum/build/bin/geth /geth && \
-  apt-get remove -y golang-1.9 git make gcc libc-dev && apt autoremove -y && apt-get clean && \
-  rm -rf /go-ethereum
-
-EXPOSE 8545
-EXPOSE 30303
-
-ENTRYPOINT ["/geth"]

containers/docker/master-alpine/Dockerfile

-FROM alpine:3.7
-
-RUN \
-  apk add --update go git make gcc musl-dev linux-headers ca-certificates && \
-  git clone --depth 1 --branch release/1.8 https://github.com/ethereum/go-ethereum && \
-  (cd go-ethereum && make geth) && \
-  cp go-ethereum/build/bin/geth /geth && \
-  apk del go git make gcc musl-dev linux-headers && \
-  rm -rf /go-ethereum && rm -rf /var/cache/apk/*
-
-EXPOSE 8545
-EXPOSE 30303
-
-ENTRYPOINT ["/geth"]

containers/docker/master-ubuntu/Dockerfile

-FROM ubuntu:xenial
-
-ENV PATH=/usr/lib/go-1.9/bin:$PATH
-
-RUN \
-  apt-get update && apt-get upgrade -q -y && \
-  apt-get install -y --no-install-recommends golang-1.9 git make gcc libc-dev ca-certificates && \
-  git clone --depth 1 --branch release/1.8 https://github.com/ethereum/go-ethereum && \
-  (cd go-ethereum && make geth) && \
-  cp go-ethereum/build/bin/geth /geth && \
-  apt-get remove -y golang-1.9 git make gcc libc-dev && apt autoremove -y && apt-get clean && \
-  rm -rf /go-ethereum
-
-EXPOSE 8545
-EXPOSE 30303
-
-ENTRYPOINT ["/geth"]