update to cassandra-driver 2.0.0 and cassandra 2.0.5

API has changed in cassandra-java-driver and {session|cluster}.shutdown() have been deprecated and replace by closeAsync() since version 2.0.0-rc3: 
[api] Renamed shutdown to closeAsync and ShutdownFuture to CloseFuture. Clustering and Session also now implement Closeable (JAVA-247).

Conflict with guava version: exclude has to be done

Warning: may break compatibility with older cassandra version (or driver in rc)