SemWeb extension for PubSubHubbub
##################################
The semhub implementation is similar to that of the pubsubhubbub hub. The following details will provide the information
of the changes made to the pubsubhubbub hub

-----Requirements
1. RDF Store or a sparql endpoint. 
2. This endpoint needs to have access to read and write a graph to store the information 
   of the subscribers and the publishers.

Note: At this point of time the sparql endpoint in the code is a localhost virtuoso. The graph name and the endpoint is static.

-----Code/Libraries Added
1. Folder SPARQLWrapper :SparqlWrapper which is a sparql endpoint interface to python. http://sparql-wrapper.sourceforge.net/
2. Files sparql_connect.py : Code to select and insert triples to an RDF Store via SPARQL Wrapper. This has to be modified according to the requirements for    the hub (Ex: SPARQL Endpoint, graph name has to be accessed through a properties file). 

-----Files Changed
1. hub.py
2. feed_diff.py

Note: The code is commented with the differeces and the addtion of new code. Search for 'SMOB' in the code and u can find the changes.

To support WebID authentication by the subscriber
--------------------------------------------------

When subscriber request to subscribe, hub must request for the subscriber private profile.
It's going to be /private by default, but subscriber should notify the hub about it before in some way.
When the hub request the subscriber /private, then the subscriber request the hub certificate (hub_cert.pem) and WebID uri (currently in /me) and the subscriber will answer with the private profile.


*Important Notes* (Julia): 
1. GAE development server doesn't support HTTPS connections!!, other restrictions too (http://code.google.com/appengine/docs/python/config/appconfig.html#Secure_URLs)
2. The provided certificate (hub_cert.pem) and public profile (/me) don't use a valid unique URI, but a localhost one.