(╯°□°）╯ ︵  Happyplan => Gulp

Pour tester (version tl;dr;)

```shell
git clone https://github.com/putaindecode/website.git
cd website
git checkout gulp
npm run init
npm i
npm start
```

Closes #119 #136

RAF:
- [x] virer hp
- [x] mettre gulp
- [x] remettre server + livereload
- [x] migrer posts vers jade+md
- [x] migrer page existantes vers jade+md
- [x] styles
- [x] remettre highlight du code
- [x] remettre disqus
- [x] remettre analytics
- [x] ignore builded part (fonts, icons.css etc)
- [x] publish go gh-pages
- [x] travis-ci
- [x] jshint
- [x] jscs
- [x] rss (jade does xml)
- [x] sitemap (same)
- [x] disable plumber when not watching so error can actually break the process (to trigger travis error)
- [ ] faire le publish sur gh-pages, (actuellement sur gh-pages-test)
- [ ] stylus -> futur proof css (rework) ?