Update Node.js support

[smaboshe]

We have added the heroku/nodejs buildpack for Node.js support. We would like to configure the versions of the tools that are used.

This commit adds a package.json file with a minimal configuration to use the same tools locally (.tool-versions) as we do in our deployment environments.

Ref:

• https://devcenter.heroku.com/articles/ruby-support#node-js-support