* Fix#130: Wrong answer for RPC server method getaccountstate
- fixed RPC Server response
- fixed RPC Server tests
- remove unused package from go.mod
* add index and type checker
* fix review comments (thx @aprasolova)
* Implemented rcp method GetAccountState
* code clean up
* Removed empty line
* Used consistently github.com/pkg/errors package. Amended error message
* Get rid of fmt.Sprintf and use either errors.Errorf or errors.Wrapf
* cosmetic changes