Stop tracking .cmus/autosave.

This is an automatically created, live state file that should not be
tracked from machine to machine.
h4x: Add git-push-backup and supplemental.

I use this to create remote backups of incomplete/ugly history that
isn't ready to be shared yet. Typically I create a bare repo on my hard
drive, and another bare repo on another drive, possibly on a network
machine. These server as poor-man backups in case my original copy gets
damaged. These typically force push everything: branches and tags.
h4x: Add template taskrc.

I still need to learn how to use task, but it sounds very useful and
like something I had been planning to build. It seems somebody beat me
to it, and did a much better job of it than I would have.