adds a second yaml configuration file for cassandra 2.0.x

[dcosson]

Solves issue #13

[dcosson]

Duplicating the file seemed like a clean way to do it, and easy to extend if there are other options that should be included or tweaked for 2.0 by default. But if you think a single yaml file with if statements is better I can change it.

[stagrlee]

Love this patch. With the latest Oracle JDK, this gets me up and running

class { 'cassandra':
  cluster_name        => 'ditCluster',
  seeds               => [ '10.0.0.17', '10.0.0.18', '10.0.0.21', ],
  package_name        => 'dsc20',
  thread_stack_size   => '256',
}

[tbarbugli]

+1