Change main entry to dist

[dy]

Hi @ianstormtaylor!
Right now it is not convenient to use this library with babelify/browserify, since that uses ES6 export and requires global browserify transform.
Changing main entry in package.json to dist fixes this problem, also that is well-established practice.

Appreciate your attention.

[ianstormtaylor]

Hey @dy, can you explain what the global transform is needed? I think the react-values.js file which package.main points to uses CommonJS requires?