cassandra: Capstan packaging support

This adds Capstanfile to build and run Cassandra with Capstan. It uses
basename variable substitution ("&") which depends on the following
Capstan pull request:

  https://github.com/cloudius-systems/capstan/pull/77

Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>
Signed-off-by: Tomasz Grabiec <tgrabiec@cloudius-systems.com>