Refactoring yo

Here are the goals:

- Don't use `yeoman-generator`, as yo doesn't generate anything I believe yeoman-generator is not the correct architecture for this project.
- Separate every commands in it's own self contained page route.
- Improve tests: remove network connection, uses correct mock on the low level methods rather than stubbing out used methods.

I extracted a first page (help) for proof of concept. Any further help is welcome on the `refactor` branch.