Create converter script

[ZoranPandovski]

Create a python script that converts all notebooks inside notebook dir to markdown files, instead of converting them one by one.

[sdtrain]

Do I also need to convert the markdown file to the following format? If yes, then from where will these data come from?

Note: Each markdown file must have:

• Title: My First Review
• Date: 2010-12-03 10:20
• Category: Review