Add support for marked markdown parser

Since @isaacs  deprecated his github-flavored-markdown as of [4e647c](https://github.com/isaacs/github-flavored-markdown/commit/4e647c15851ebf85fc4fa0fababaef9e676acc43) in favor of chjj's marked package, this pull request adds support for that markdown parser.

I have copied the marked package into node_modules 
from: https://github.com/chjj/marked @ b9c2a3dda3bdd6547cde60292f246970504b5f03
This seems to be the way the others are included.

I'm hoping you have plans to use ```npm install``` in the future.