Adding ESGF_REPO to build script.

#!/bin/sh

# script to build (and optionally push) all ESGF Docker images

# note: must define env variable ESGF_REPO to point to ESGF distribution repository

# Example: export ESGF_REPO=http://distrib-coffee.ipsl.jussieu.fr/pub/esgf

#

# Usage:

# docker_build_and_push_all.sh <version> [--pushit] 

# Example:

  echo "BUILDING MODULE=$img PUSH=$pushit\n"

  # build the module

  docker build --no-cache -t esgfhub/$img .

  docker build --no-cache --build-arg ESGF_REPO=$ESGF_REPO -t esgfhub/$img .

  # optionally push the module to Docker Hub

  if [[ $pushit == *"push"* ]]; then