#169 Admin on teams

* adds admin column on team index view
* refactors Team model, so multiple members can become admins
* adds team migration for switch from fkey->m2m structure
* renames 'Group' to 'Permission' on user index view to avoid confusion between 'Groups' and Teams
* adds new autocomplete route for team-admin selection based on already selected members of the TeamForm

user/models/team.py

@@ -11,7 +11,7 @@ class Team(UuidModel):
     name = models.CharField(max_length=500, null=True, blank=True)
     description = models.TextField(null=True, blank=True)
     users = models.ManyToManyField("user.User", blank=True, related_name="teams")
-    admin = models.ForeignKey("user.User", blank=True, null=True, related_name="+", on_delete=models.SET_NULL)
+    admins = models.ManyToManyField("user.User", blank=True, related_name="+")
 
     def __str__(self):
         return self.name
@@ -104,6 +104,19 @@ class Team(UuidModel):
 
         """
         self.users.remove(user)
-        if self.admin == user:
-            self.admin = self.users.first()
-            self.save()
+        self.admins.remove(user)
+        self.save()
+
+    def is_user_admin(self, user) -> bool:
+        """ Returns whether a given user is an admin of the team
+
+        Args:
+            user (User): The user
+
+        Returns:
+            user_is_admin (bool): Whether the user is an admin or not
+        """
+        user_is_admin = self.admins.filter(
+            id=user.id
+        ).exists()
+        return user_is_admin