#101 Team sharing tests

* 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

api/tests/v1/update/intervention_share_update_put_body.json

@@ -0,0 +1,8 @@
+{
+    "users": [
+        "CHANGE_ME"
+    ],
+    "teams": [
+        "CHANGE_ME"
+    ]
+}