Basic project structure

Here is the PR about the project architecture. For now, I didn't changed anything in the sass codebase, but I have only included some workflowy things. 

* First you will have to `npm install`, this will install all dependencies.
* Then, just type `gulp` in your terminal. This start a webserver (including livereload), open it up in your browser, and will watch for any changes to the sass codebase.
* I splitted the hole repo up in 2 directories: one for the demo website and one for the sass code.
* I added all `.css` files to `.gitignore`, those aren't needed in the repo.
* Changed readme

If there's anything you want to see changed, ping me ;-) Can you review the info in package.json? Is it correct?