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

The JSON output was not following the standard and tools such as [Jq](http://stedolan.github.io/jq/) was not able to parse the MongoDB BSON/JSON output. Now, the output is standard JSON and Jq can process properly the output:

    python3.3 search_fulltext.py -q Java -f | jq '.cvss'

The fix has been on the fulltext search tool and the standard search tool.

Some examples are available here:

https://gist.github.com/adulau/5428958