Add ROOTFS to gitignore

Many modules use the "ROOTFS" directory for staging a filesystem. Add
that to gitignore as it's a temporary build artifact.

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

The "start-cassandra" script has been long obsolete. It was added before
we had a module systes so lets just kill it.

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