Project layout refactor, better production settings

The project layout did not follow Java classpath conventions. The
project source filenames did not correspond to declared namespaces.

Bump Om dependency.

Use react_with_addons.js as the externs file, disable noisy Google
Closure warnings. Cleanup index.html to only include the final
production main.js. The total gzipped JS payload for Goya is now 75K.