[Bug]: Right Click - When altering a keyspace, only use the values that have been altered

[millerjp]

When changing durable writes from true to false

The CQL inclused the alter for the keyspace replication

ie

ALTER KEYSPACE system_traces
WITH replication = {'class':'SimpleStrategy','replication_factor':'2'}
AND durable_writes = false;

It should have been

ALTER KEYSPACE system_traces
WITH durable_writes = false;

This is the behaviour for all alters - we should only be passing in changed values