trilby's Person gains a key_name property

kepi/trilby_api/models/person.py

@@ -173,6 +173,10 @@ class Person(models.Model):
                 'username': self.local_user.username,
                 })
 
+    @property
+    def key_name(self):
+        return self.url + '#main-key'
+
     @property
     def following_count(self):