Modify notifications and add picture for team and pack

app/config/config.yml

app/config/services.yml

src/ApiBundle/Controller/DefaultController.php

src/BackendBundle/Controller/EntityBrowserController.php

src/BackendBundle/Controller/NotificationController.php

src/BackendBundle/Entity/Device.php

src/BackendBundle/Entity/Device.php~

src/BackendBundle/Entity/Notification.php

src/BackendBundle/Entity/Notification.php~

src/BackendBundle/Entity/Pack.php

src/BackendBundle/Entity/Prediction.php

src/BackendBundle/Entity/Team.php

src/BackendBundle/Form/AddScoreType.php

src/BackendBundle/Form/NotificationType.php

src/BackendBundle/Form/PackType.php

src/BackendBundle/Form/PredictionType.php

src/BackendBundle/Form/TeamType.php

...ckendBundle/Repository/NotificationOnDeviceRepository.php

src/BackendBundle/Repository/PackRepository.php

src/BackendBundle/Repository/PredictionRepository.php