googleapis-20190724-bp154.1.20

- Update to version 20190724:
  * Synchronize new proto/yaml changes.
  * Bump gapic-generator version
  * Add bazel build instructions to README
  * Add bazel build output to gitignore
  * Rollback remaining parts of #273
  * use latest artman image
- Remove BUILD file - newest googleapis already contains all files
  needed for Bazel and Envoy.

- Add BUILD file compatible with Envoy.

- Do not require Python 2.4.
- Fix rpmlint errors and warnings.

- Downgrade to version 20180523. It's the newest version compatible
  with Envoy, Istio and its dependencies. No other packages are
  going to be affected by this change.

- Initial version 20190109