scripts: add fix_system_distributed_tables.py
scripts: add fix_system_distributed_tables.py

This script validates schemas of distributed system keyspaces:
system_traces and system_auth.

It tries to add the missing columns and checks that the existing columns
have expected types.

In case of any problem the corresponding info message is printed and non-zero exit
status is returned.

Extra columns are ignored.

The validation function may also be called from another Python program.
It returns True in case of success and False otherwise.

Signed-off-by: Vlad Zolotarov <976c0f8d0852ed6439ad273880b400a75a7c41d0@scylladb.com>
Message-Id: <1490195645-29905-1-git-send-email-976c0f8d0852ed6439ad273880b400a75a7c41d0@scylladb.com>

duarten/scylla,duarten/scylla,scylladb/scylla,avikivity/scylla,scylladb/scylla,scylladb/scylla,avikivity/scylla,avikivity/scylla,scylladb/scylla,duarten/scylla