Download nltk packages in IPython as vagrant user

* 4 Example 6. Hacking on Google Plus data in the interpreter with NLTK
    * nltk.download('stopwords')
* More sophisticated sentence detection
    * nltk.download('punkt')
* Part of speech tagging for tokens
    * nltk.download('maxent_treebank_pos_tagger')
* Named entity extraction/chunking for tokens
    * nltk.download('maxent_ne_chunker')
    * nltk.download('words')
* Example 5. Using NLTK’s NLP tools to process human language in blog data)
    * nltk.download('stopwords')