message: chore(account-lib): export polkadot interface
  In order to use the type def outside of account-lib, we will
  need to export the type like eth or celo do.
  Ticket:
diff: import * as Utils from './utils';
  +import * as Interface from './iface';
  export { KeyPair } from './keyPair';
  export { Transaction } from './transaction';
  @@ -8,4 +9,4 @@ export { TransferBuilder } from './transferBuilder';
  export { AddressInitializationBuilder } from './addressInitializationBuilder';
  export { UnstakeBuilder } from './unstakeBuilder';
  export { TransactionBuilderFactory } from './transactionBuilderFactory';
  -export { Utils };
  +export { Interface, Utils };
  