Build gh-pages with grunt

- [x] check https://github.com/tschaub/grunt-gh-pages
- [x] check https://github.com/cburgdorf/grunt-release-branch
- [x] try it
- [x] better solution?

### Taks todos

- [x] create ng app for the docs
- [x] code hightlight
- [x] fix navbars
- [x] `$anchorScroll()`
- [x] deploy it on `gh-pages`
- [x] add grunt task for deploying