Adds basic testing and fixes includes with more than one argument. Generates source maps for prose.js and test/index.js

Update with make install

Run tests with npm test

Live previews just got better with support for jekyll includes in live previews.
For example:
{% include author-info.html author="Robert" %}

Fixes live previews

• Uses the stashed content and metadata for the preview, so that you can preview before saving.
• Keeps the file in edit mode when using live preview, which opens a new window right now.