* adds mail sending logic for new notification setting
* adds new templates for user and team based sending
* enhances all email template layout
* adds translations
* adds restorable delete functionality to Team model
* refactors minor code model parts by introducing DeletableObjectMixin
* only non-deleted Teams can be chosen for sharing
* deleted Teams can be restored using the proper function on the backend admin
* deleted Teams do not provide
* adds migration
* adds new app to project
* adds relation between User model and new APIUserToken model
* adds first implementation for GET of intervention
* adds basic code layout for future extension by having new versions
* adds mail sending if shared data is deleted
* adds/updates translations
* refactors recording mails into separate email template folder email/recording
* moves mail sending to celery worker using shared_task in konova/tasks.py
* adds mail sending for shared access given
* adds UserNotification settings checks for mail sending
* adds/updates translations
mpeltriaux