This project won't be published because there have been several projects in npm repository. It has some simple functions and should meet your basic requirement.
create global link with npm link
# clone this repository
git clone https://github.com/vamcc/markdown-server.git
# install and link
cd markdown-server
npm install && npm link
switch to any folder and type following command
markdown
Now, it only contains a server to serve static resource and preview markdown file. Make it more interesting by yourself.