Revert RepoApi to explicitly query for token

Instead of using the current wiki's token, RepoApi queries the actual Repo instance for
an edit token again for being able to use an RepoApi instance on the client.

Change-Id: Id45adfb73fccbea162510ae95e36389bdbe7496f
(cherry picked from commit bb985619719a3d9bbcefc887589f908a4c6eecf3)