DeltaAware support for conditional operations

Current delta-aware approach is implemented only in PutKeyValueCommand and ApplyDeltaCommand. This implementation does not allow to execute conditional delta-aware commands - or rather it does not allow to return any kind of value (the condition itself can be implemented inside the delta).

One use-case when this would be required is equivalent of AtomicLong.getAndIncrement(). Currently we can implement this using

Long previous;
do {
    previous = cache.get(key);
} while (cache.replace(key, previous, previous + 1);

which requires at least two RPCs. With more generic interface, such as JCache's EntryProcessor this could be implemented using single RPC.

(so, this JIRA is basically a request to native support for EntryProcessor)