Make CAS retry logic configurable

Make CAS retry logic configurable:

One should be able to disable the internal CAS retry loop (when the condition is not met) and let the client choose how to do retries (so the client does not have to incur the server side random sleep of up to 100ms). Basically let the client handle all CAS retries in a manor it sees fit.

Secondly the hardcoded sleep up to 100ms that happens when cassandra fails to meet the CAS condition should be configurable.

• The max duration should be configurable
• The algorithm used to choose the duration should be configurable (Random, Exponential, etc).