replace git_repository rule with new http_archive rules (#401)
replace git_repository rule with new http_archive rules (#401)

- Bazel 0.12.0 release notes say:
  The native http_archive rule has been deprecated. Use the Skylark
  version available
  https://blog.bazel.build/2018/04/11/bazel-0.12.html

- Also upgrade some of the dependencies with their latest releases
bazelbuild/rules_docker,bazelbuild/rules_docker,bazelbuild/rules_docker,bazelbuild/rules_docker