* Add build test for Flutter codelabs

* Fix indentation in build test script

* Correct filename for the codelabs build test run by travis

* Change if statement to elif

* Replace echo statements with set -x

* Add BSD-style license

* Add codelabs build test to Cirrus

* Remove codelabs_build_test from Travis.

* Remove codelabs_build_test from travis_script.sh

* Update documentation for codelabs_build_test.sh

* Update readme for build test

* Add link to open a new issue to MDC-Flutter

* Add phrase to address "if you think you really need to break this test, please escalate this"