Update to 3.6.5

Changelog:
2016-02-20  v3.6.5  allow creator check to be bypassed during mirroring

                    handle new style ssh fingerprinting correctly (thanks to
                    Robin Johnson)

                    allow pre-auto-gc as a repo-specific hook

                    optimise mirror pushes for heavily used repos

                    create-with-reference trigger: on repo creation, setup
                    objects/info/alternates for a server side alternate object
                    store.

                    'mirror status all all' prints a list of repos that have
                    *some* error, which is arguably more useful for further
                    action/processing

                    allow incrementally adding more repo-specific hooks

(ryoon)