MANIFEST.in does not include React 16 bundles in v0.12.0

[mjclawar]

The MANIFEST.in file does not include the React 16 bundles, which means that updating the react version does not work in development in other projects (e.g., this PR in dash-core-components), starting in v0.12.0.

Addressing this issue requires updating the MANIFEST.in to

include dash_renderer/bundle.js
include dash_renderer/react-dom@*.min.js
include dash_renderer/react@*.min.js

to handle all react and react-dom files via blob for publishing to PyPI