Print Buildifier version, if available. (#533)
Print Buildifier version, if available. (#533)

This commit is a part of https://github.com/bazelbuild/continuous-integration/issues/530
bazelbuild/continuous-integration,bazelbuild/continuous-integration,bazelbuild/continuous-integration,bazelbuild/continuous-integration,bazelbuild/continuous-integration,bazelbuild/continuous-integration,bazelbuild/continuous-integration,bazelbuild/continuous-integration