message: fixed FileUnit populate, so display works correct
diff: import * as mongoose from 'mongoose';
  import {IUnitModel} from './Unit';
  import {IFileUnit} from '../../../../shared/models/units/IFileUnit';
  +import {User} from "../User";
  interface IFileUnitModel extends IFileUnit, IUnitModel {
  populateUnit: () => Promise<IFileUnitModel>;
  @@ -28,6 +29,9 @@ const fileUnitSchema = new mongoose.Schema({
  });
  fileUnitSchema.methods.populateUnit = async function() {
  + if (this.unitCreator) {
  + this.unitCreator = await User.findById(this.unitCreator);
  + }
  return this.populate('files').execPopulate();
  };
  