Exports using module.exports for node v8 support

[cammanderson]

By using module.exports for the class, node v8 (Current Node LTS) is able to load the library without babel polyfills or other transpiler.

I ran the 'pp' task which passed, and this is the result. I have included the src using node v8 and it loads without any further runtime.

[mhelvens]

Sorry for the delay in responding.

First thought: Moving the source-code away from ES6 modules is like taking a step backward. Your motivation is to be able to load the library without requiring the polyfill? That's fair enough, but I don't see a real downside to having a build-step. Want you like to try to provide that build-step?

Second thought: For libraries I don't see the point of committing package-lock.json (or yarn.lock) to version control. It won't be used by a project that has the library as a dependency. (Or did that change?)

Third thought: Have you looked at the failing CI?