* adds geom back writing to form field in case of invalid geometry, so the invalid geometry will be shown again
* updates tests
* fixes bug where race condition of celery workers could lead to duplicates in parcels (needs migration)
* adds tests for team sharing
* extends the API for team sharing support
* adds shared_teams property shortcut for ShareableObjectMixin
* adds full support for team-based sharing to all views and functions
* simplifies ShareModalForm
* adds/updates translations
* adds team sharing field to share form
* splits sharing logic into user based and teams based
* adds TeamAdmin for admin backend
* adds validity check on Team name -> only unused names shall be valid
mpeltriaux