Bootstrapping doesn't work on new clusters

This is an edge case.

1. start a clean 3 node cluster with autobootstrap on.
2. load some data.
3. bootstrap in a 4th node.

the logs in the 4th node will indicate that data was not received. If you restart the cluster in between steps 1 and 2, or 2 and 3, boot strapping works fine.

I find that waiting on the table flush when making the streaming request solves the problem (see patch).