cassandra: refactor versioning

This change:
- refactors the packages so it is easier to create and update new versions of
  cassandra.
- fixes a bug where Cassandra will not connect to another member unless
  LD_PRELOADing libstdc++.so. Without that change, it generates a stack trace
  and dies with exceptions regarding org.xerial.snappy.
- restricts platform to linux as procps is also linux only.