Add support for GetNameInfo

[Paul Grau]

Spec: https://docs.aergo.io/en/1.2/api/rpc-autogenerated.html#GetNameInfo

[Aaron (Yun Woo) Park]

db588a0

I committed to support 'GetNameInfo'. It will be included in release version 1.2.4.

[Aaron (Yun Woo) Park]

It's gonna be more advanced after supporting with create/update name system.