adds support for commented JSON configuration

Our team likes to annotate JS(ON)-based configuration files and adding extra information to settings so "the next guy" knows why certain settings were made.

When possible, we use JS-based config files which support comments natively. In case we have to use JSON, we parse it with `cjson` so as to not break `JSON.parse` with inline-comments.

With this changeset, I added support for parsing commented JSON files (by means of `cjson`). I have also updated the tests.

tl;dr: added support for comments in nodemon.json