Memcached.RemoveAsync with durability does not throw NotSupportedException

The RemoveAsync variants that include durability requirements (PersistTo & ReplicateTo) are not supported on MemcachedBuckets. The sync versions of Remove throw NotSupportExceptions as expected.

The following methods should return NotSupportedException instead of trying to remove the document key:

RemoveAsync(string, ReplicateTo)
RemoveAsync(string, ReplicateTo, PersistTo)
RemoveAsync(string, long, ReplicateTo)
RemoveAsync(string, long, ReplicateTo, PersistTo)
RemoveAsync(Document<T>(), ReplicateTo)