#229 Shared users mandatory on admin

* changes mandatory state of users and teams on admin backend to optional (as expected by the model)
* adds team selection to admin backend

intervention/admin.py

@@ -14,7 +14,8 @@ class InterventionAdmin(BaseObjectAdmin):
     ]
 
     filter_horizontal = [
-        "users"
+        "users",
+        "teams",
     ]
 
     def get_fields(self, request, obj=None):
@@ -25,6 +26,7 @@ class InterventionAdmin(BaseObjectAdmin):
             "checked",
             "recorded",
             "users",
+            "teams",
             "geometry",
         ]