Documentation added for the keywords visualization.

Clarification on the use of NLTK for stemming the keywords and
how to use it.
JSON output is fixed

JSON output is now standard format and using the bson/json conversion.

You can now use jq to process the results:

        python3.3 search_fulltext.py -q Java -f | jq '.cvss'
JSON output is fixed

    JSON output is now standard format and using the bson/json conversion.

    You can now use jq to process the results:

JSON output is fixed

The BSON format from MongoDB format is now represented following
the standard JSON representation. Jq can now directly processes
the results:

    python3.3 search_fulltext.py -q Java | parallel -j 10 python3.3 search.py -r -c | jq '. | {cvss, summary}'
Default output of search is the list of CVE-ID

If no output format is specified, the default output is the CVE-ID.
Merge pull request #9 from adulau/master

JSON output fixed for search (fulltext and MongoDB) + a fix in the documentation