v2.0.0

• New material theme: a clean responsive style to help bootstrap your deck.
• Travis CI deployment now uses deploy keys instead of personal access tokens.
  If you use this feature you must follow the new setup instructions.
• Deploy keys can be overridden via the DEPLOY_KEY
  environment variable.
• Switch to using rake-jekyll for git based deployment.
  You may now set the SOURCE_BRANCH environment variable
  to enable testing on all other branches.
• Add staging environment support for Travis CI builds.
• Set staging site CNAME with CNAME environment variable.
• Optimize Travis build by adding bower to package.json.
• Bump most dependency versions.