LocalPerson gains get_followers_collection() and get_following_collection(),

which are aliases for the followers and following properties.

This isn't elegant, but it makes the views easier. When we fix
issue 64, we should return to the question of these accessors
for Persons in general.

kepi/trilby_api/models/person.py

@@ -613,6 +613,12 @@ class LocalPerson(Person):
             rel_following__following = self,
             )
 
+    def get_followers_collection(self):
+        return self.followers
+
+    def get_following_collection(self):
+        return self.following
+
     @property
     def inbox_url(self):
         return uri_to_url(settings.KEPI['USER_INBOX_LINK'] % {