Set the replication authGroup for github to Anonymous Users.
Enable the "mirror" option which "will remove remote branches that absent
locally or invisible to the replication (i.e. read access denied via
authGroup option)."
Disable replicatePermissions which will cause permissions-only projects and
the refs/meta/config branch not to be replicated. I'm ambivalent about
refs/meta/config, but disabling permissions-only projects will remove
the periodic errors we get when trying to replicate All-Projects to github.
Change-Id: I9c302b68e0a213d35683d7105341788923c5770a
67a085ba7d
