Stellar core build docker image alpine

Dockerfile

# Image: globegitter/stellar-core-build:alpine-3.6
FROM alpine:3.6

RUN apk add --no-cache --virtual=pandoc-deps wget ca-certificates && \
    wget https://gitlab.com/ConorIA/alpine-pandoc/raw/master/conor@conr.ca-584aeee5.rsa.pub -O /etc/apk/keys/conor@conr.ca-584aeee5.rsa.pub && \
    echo https://conoria.gitlab.io/alpine-pandoc/ >> /etc/apk/repositories && \
    apk add --no-cache --repository http://dl-3.alpinelinux.org/alpine/edge/testing cmark && \
    apk add --no-cache openssh git build-base pkgconfig \
    autoconf automake libtool bison flex postgresql-dev pandoc && \
    apk del pandoc-deps