Nikola with sphinx-design

• Sample Nikola site using sphinx-design directives for bootstrap-like cards without writing raw HTML.
• Not everything is working (panels do, icons do, drop-downs don't).
• Checkout recusrively, sphinx-design is included as submodule.
• Needs a recent sass compiler (otherwise you get errors about math.div).
• Run nikola build or nikola auto as usual.
• plugins/sphinxdesign/sphinxdesign.py contains Sphinx stubs so that sphinx-design can be loaded and used unmodified as if inside sphinx.
• The sample page is composed from examples showing various components of sphinx-design.