Added a blog post about Natural Language Processing using Python and NLTK.

This weekend the [Google Developer Group in Cairo](http://www.gdgcairo.org/ "GDG Cairo") arranged 2-days workshops followed by a hackathon. During this event, I organized a workshop about [NLTK](http://nltk.org/ “Natural Language Toolkit”) and the use of Python in Natural Language Processing (NLP). In this post I summarize the concepts discussed in the workshop.