Breaking changes:
- The RPC method uses PlatformAddress only.
- Replace 'isTestnet' option in PlatformAddress and AssetTransferAddress with 'networkId' option.
- Add an error field to Invoice.
- Remove the RLP methods from Invoice.

Integration tests passed with CodeChain@0.1.0 (f11b14d060361b3ba2d5f09791ed7706e96c3a13)