Update WDS to v0.11.0 and change markdown renderer
This release includes a Draft U.S. Web Design Standards update, a new markdown renderer, and a whole batch of fixes and testing work:
- Update the WDS to v0.11.0
- Changes our markdown renderer from redcarpet to kramdown
- Markdown and markup fixes in old blog posts
- Improve unordered list styling #2139
- Improve blockquote and pull quote styling #2140
- Removes duplicate hero images for many old blog posts
- Starts a styleguide that lives at /styleguide/
- Adds rspec ruby testing framework and some tests for ruby plugins #2153
- Updates CONTRIBUTING.md text for filing pull requests #2012
- Adds a codeclimate config #2157