notify: change behavior of "changegroup" hook
Change the behavior so that the sender (the "From" header in the notification
mail) in case of the "changegroup" hook is the user that did the first commit
in the changegroup. The option is configurable, if you set "notify.fromauthor"
to "True" in your config, the new behavior is activated. If you do not set the
option, the behavior is as before. The commit adds to an existing test to show
various aspects of the changed behavior.
(binary:application/octet-stream)