Update Readme

[dewski]

The readme installation is a bit out of date. Could this be updated?

[lpgauth]

Yes, please. I'm trying to use this, but I have no clue how to setup the connection to Cassandra and there's no documentation...

[SethThomas]

I agree. I'd love to see either a "Hello World" Rails3 app using cassandra_object or a quick tutorial on how to get started once the software is installed.