message: API: Remove unused NotificationController imports
diff: import {
  - Authorized, BadRequestError, Body, CurrentUser, Delete, ForbiddenError, Get, InternalServerError, JsonController, NotFoundError, Param,
  + Authorized, BadRequestError, Body, CurrentUser, Delete, Get, JsonController, NotFoundError, Param,
  Post, Req,
  UseBefore
  } from 'routing-controllers';
  import passportJwtMiddleware from '../security/passportJwtMiddleware';
  import {
  - NotificationSettings, API_NOTIFICATION_TYPE_NONE,
  - API_NOTIFICATION_TYPE_CHANGES_WITH_RELATIONIONSHIP, API_NOTIFICATION_TYPE_ALL_CHANGES,
  + NotificationSettings,
  + API_NOTIFICATION_TYPE_ALL_CHANGES,
  } from '../models/NotificationSettings';
  import {Notification} from '../models/Notification';
  import {Course} from '../models/Course';
  @@ -15,7 +15,6 @@ import {IUser} from '../../../shared/models/IUser';
  import {ICourse} from '../../../shared/models/ICourse';
  import {ILecture} from '../../../shared/models/ILecture';
  import {IUnit} from '../../../shared/models/units/IUnit';
  -import {INotification} from '../../../shared/models/INotification';
  import {Request} from 'express';
  import {SendMailOptions} from 'nodemailer';
  import emailService from '../services/EmailService';
  