Recommend lesscpy for text/less

The nodejs based less.js includes heavy dependencies and is not available on all Linux distributions by default.  Using a pure-Python LESS compiler can be fetched from PyPI and thus better integrated into automated deployment and testing.

I guess this isn't optimal yet, but I'd like to make this a starting point for a discussion. Whether or not it makes sense to recommend a pure-Python solution by default and if that would allow for deeper integration (rather than just calling the binary).