Improved OSS flow and lint reporting

Summary:- lint bot is now managed by Circle CI
- checked that flow and lint errors are caught both by bot and CI
- flow fix for npm 3
- Travis is now using npm 2 and Circle CI npm 3
- Refactored Travis script to be able to be able to fail on multiple lines
Closes https://github.com/facebook/react-native/pull/6508

Differential Revision: D3069500

Pulled By: davidaurelio

fb-gh-sync-id: 02772bf1eae5f2c44489c2e3a01899428a9640cb
shipit-source-id: 02772bf1eae5f2c44489c2e3a01899428a9640cb