Add branch-alias

This way people can require "0.3.*" and get stable vs unstable
versions depending on their minimum-stability, without having to
deal with the pains of dev-master.
Merge pull request #368 from igorw/patch-1

Add branch-alias
Add support for media query variables #335
add test for variable in media
add unit function, fixes #367
support nested interpolations #345
support interpolation inside of selectors fixes #370 #372 #369 #356
performance boost for selector parsing with interpolations
fixed a typo
Merge pull request #381 from nyordanov/master

Minor typo in toRGB($color)
version bump
remove mysterious line, fix #384
Update docs.md

Changed typo "an" -> "and"
Merge pull request #389 from quasipickle/patch-1

Update docs.md