Retry on CASWriteUnknownException

[amorton]

We are currently rwriting the CqlProxyRetryPolicy as part of that we should implement the onErrorResponseVerdict method and retry when the CASWriteUnknownException error is thrown.

I am working on the driver error messages, this happens when the propose phase of the paxos transaction fail to get the QUOURM consistency level. We can retry (up to the regular retry count) because we will are using the the LWT conditions in the CQL statement the statement is idempotent.

our high level retry in the reactive programming model will handle retrying due to the LWT not being applied.

[amorton]

Same for the TruncateException , we should retry and it will be handled in the onErrorResponseVerdict.

[amorton]

And for the UnavailableException, we should handle that in onUnavailableVerdict currently it has 1 retry and is not configured.

[amorton]

Stil valid.