Merge pull request #13 from stevekinney/add-rb-as-ruby-shorthand

Add rb as a shorthand for Ruby
Merge pull request #14 from stevekinney/match-single-quotes-in-code-blocks

Match single quotes in code blocks
Detect and respect YAML frontmatter
Custom font for YAML frontmatter
Merge pull request #16 from stevekinney/support-yaml-front-matter

Detect and respect YAML frontmatter