Add support for Apache Cassandra DB

Install, configure and initialize Apache Cassandra v2.0 database for FrameworkBenchmarks.
Can you entirely remove the chown? Note we are not superbly concerned with
security here, the point is just to get it online.

If you can't remove it, my vote would be to do whatever you need to ensure
that running "--install database" can complete without external dependency
(eg it should run OK regardless of if tfb exists or not). This suggests
that you should create a new user just for Cassandra