Ensure library consumers pull built version

[arindam1993]

Fixes #1030
Fixes #1032

Depending on users bundler configuration, some bundlers would point to the index.js file, and this would let the users bundler take over build responsibilities.

With this change, all usage of this library will always point to the built bundle.Had to make imports in a few tests explicit as a result.

Fixes #970
I also update the build config to handle node builtins used by dependencies in a cleaner fashion, by declaring externals rollup appends require's to the top of the bundle, I switched that to using the plugin that provides shims for node builtins.

These shims get automatically treeshaken out from the bundle.

I tested this by using an external webpack project and it works great with no errors.

[bradgreens]

Thank you @arindam1993