PR #51: Pin TravisCI Bazel installation to v0.20.0
PR #51: Pin TravisCI Bazel installation to v0.20.0

Please approve this CL. It will be submitted automatically, and its GitHub pull request will be marked as merged.

Imported from GitHub PR https://github.com/tensorflow/adanet/pull/51

To fix broken build: https://travis-ci.org/tensorflow/adanet/builds/470180930
Newly passing build: https://travis-ci.org/tensorflow/adanet/jobs/470210477

Prevent future builds from breaking when Bazel releases a new package.

Follows instructions from https://docs.bazel.build/versions/master/install-ubuntu.html.

Copybara import of the project:

  - fc0e9a07560c366b0da89c9d7d9ccdfe3b53a158 Try bazel binary installer by Charles Weill <weill@google.com>
  - 40abfd6f5360676e4f7ea19207cdd2f4328847e1 Add required packages. by Charles Weill <weill@google.com>
  - 6ff8ba3da9482577875de1e306f1c5fc2371f198 Specify --user by Charles Weill <weill@google.com>
  - 33619a80e5bc37d56147b3ab4b101026d431b621 Add HOME/bin to PATH. by Charles Weill <weill@google.com>
  - d9b8f5a277d7907d9317b6ca00f9228003c096f6 Merge 33619a80e5bc37d56147b3ab4b101026d431b621 into 2387c... by Charles Weill <c@weill.io>

PiperOrigin-RevId: 226226737

tensorflow/adanet,tensorflow/adanet