Use bless v4.0

The current version (v3.0.3) takes a significant amount of time on very large css files in terms of file size. His 4.0 branch is faster. I'm having bless pointed at my fork's dev branch instead since there are a few changes that were needed in order for 4.0 to work with our css.
What is available in your fork that is not in the published npm? Is there an associated pull request for that change that should be linked here?