message: removed unused import in EncryptedMessage test
diff: import {expect} from 'chai';
  import {Account} from '../../../src/model/account/Account';
  -
  -import {PublicAccount} from '../../../src/model/account/PublicAccount';
  -import {NetworkType} from '../../../src/model/blockchain/NetworkType';
  import {EncryptedMessage} from '../../../src/model/transaction/EncryptedMessage';
  import { TestingAccount } from '../../conf/conf.spec';
  