Now defaulting -use_srv_shard_locks to true. Been working
in dev for a while now.
Moving blp_checkpoint table creation to the MultiRestore code.
Fix keyspace id format
Avoid serializing to string in streamlog.

Some log consumers wish to receive structured messages. This is best
evidenced by the logz handlers parsing the message strings they receive.
Implement error case of downcasts in streamlog consumers.

This should never happen (famous last words).