Support putNoIndex interface on kvstore.

[dangleptr]

Subtask of #71

When updating data with index, we should read the old data to construct old index-key, then we delete the old index-key, finally insert the new data and new index.

This should be atomic, we could support it in kvstore.

[darionyaphet]

Here are some cost when serialization and deserialization.

Should we save the indexed values in some place to avoid it ?

[darionyaphet]

You mean support read the old data, delete the old index-key, insert the new data and new index in kvstore?

[sherman-the-tank]

We need more subtle design on this.

[dangleptr]

redundant with #458