bazel-rules-proto-20190801-bp154.1.20

- Updated to version 20190801
  * Add CODEOWNERS for rules_proto
  * [docs] Add reference to automatic buildifier fix
  * Fix issues to get CI to green

- Update to version 20190719:
  * Add migration tag to rules and export some more native symbols
  * Remove copyright headers from .git{attributes,ignore}
  * Address comments from review
  * Remove non-essential copyright headers

- Initial release 20190115