Allow functionality to be used in node.js directly.

[TimDaub]

Hi,

I have a project that wants to use this library directly from within nodejs. I'd like to import the functions in .e.g. the index.js file. Hence, these functions should be exported. Right now, I'm using the provided binary. It's really messy though: https://github.com/0xdefaceme/etherscan-uploader/blob/master/index.js#L41

If I have time today, I'll send a PR.