Tarball installation should use version specified in override_attributes

I tried to install version `2.0.1` of cassandra via tarball recipe and noticed an issues: recipe always downloads default version of cassandra (`apache-cassandra-2.0.3-bin.tar.gz` for example) but saves it into file with name `apache-cassandra-2.0.1-bin.tar.gz`.

PS What do you think about rewriting tarball recipe using `ark` functionality? As I see `ark` cookbook is already in dependencies of  `cassandra-chef-cookbook`...