Bump VERSION to 4.0.0.alpha.
Merge branch 'stable'
cleaning up some of the documentation of at-root with a slightly more complex example. sass/sass#1462
Merge pull request #1463 from hcatlin/at-root-docs

At-Root Documentation Fix
typo fixes
Merge pull request #1506 from vlajos/typofixes20141102

typo fixes
Add list-contains function

Check whether or not a given item exists within a list

Usage:

```scss
$list: 1 2 3 4
list-contains($list, 2) => true
list-contains($list, 5) => false
```