Camel case and NPM test

I made the change from PascalCase to camelCase as discussed #18. I also changed the documentation into setting the variable to the module as `oauth2` instead of `OAuth2`.

In addition I added `npm scripts` for test and test watch, as I think it's natural to at least have `npm test`. As for me, being used to node modules, the first instinct I have is to test by doing `npm test`. I don't know whether or not you agree with me? In any case, I can delete the commit per request.