Add kwargs.js [author]

kwargsjs is a small tool that helps you define functions with kwarg capabilities just like python. As of today it has **95** stars on github. kwargsjs is also on npm. 

Sources of the files are from the [repository itself](https://github.com/serkanyersen/kwargsjs), I created the minified version myself and run the [kwargs test suite](https://github.com/serkanyersen/kwargsjs/blob/master/tests/test.js) against it.