Docs: use jsdoc annotations for rule description

As I promised at #129, I have used JSDoc for better documentation.
I have moved all descriptions into to the rule definition. To build documentation you need to run `npm install` that will install jsdoc, after that run `npm run doc` which will generate the documentation.
Also you can preview resulting documentation on my [gh-pages](http://catatron.com/node-jscs/)

I hope you accept the changes. If you have a question, I will be glad to help