Skip yarn test for now (#287)

Summary:
This isn't working on Travis yet and will skip the subsequent steps
which do provide value if run right now.
Pull Request resolved: https://github.com/facebook/flipper/pull/287

Reviewed By: jknoxville

Differential Revision: D10161725

Pulled By: passy

fbshipit-source-id: 3502230e842c9451e8f33309b500a720cdaa5514

.travis.yml

@@ -35,7 +35,6 @@ matrix:
         - yarn
 
       script:
-        - yarn test
         - yarn lint
         - yarn build --mac --version=$TRAVIS_BUILD_NUMBER