Search interface to the fulltext index (in Whoosh)

The search interface to query the Whoosh index to find the matching
CVEs and output the CVE from the MongoDB collection.

python3.3 search_fulltext.py -q NFS -q Linux
 -> to query NFS and Linux and output the list of matching CVEs

python3.3 search_fulltext.py -q NFS -q Linux -j
 -> to query NFS and Linux and output the JSON for each CVE
Crude indexer of CVEs to a Whoosh fulltext index.

The fulltext indexer is relying on Whoosh.

http://packages.python.org/Whoosh/

The indexing is done by enumerating all items from
the MongoDB CVE collection and indexing the summary text of each
CVE. The Path of each document is the CVE-ID.

The current indexing is indexing all CVEs from the MongoDB. This need
to be improved when new items are updated (TODO).

The fulltext indexing is done to overcome the limitation of MongoDB
regarding fulltext indexing and to improve response time for non-indexed
records (especially for the XMPP bot).
Basic explanation for the fulltext indexing

db_fulltext.py and search_fulltext.py added in the documentation
to explain their uses. Be aware that the db_fulltext.py is still
at the early stage.