Update only if certain git files change or if a non-git file changes
Update only if certain git files change or if a non-git file changes

To reduce noise and unnecessary updates, we're only watching for changes
in the .git folder that we care about and ignoring the rest.

.git/index changes when staging/unstaging
.git/HEAD changes when checking out branches, committing, and
pushing/pulling.
.git/config changes when pushing to a new remote and setting up
tracking.

On Windows nsfw does something a bit funky - when the contents of the
.git folder change, in addition to reporting that individual files
change, it reports that the directory itself changed and lists `.git` as
the changed file name. So we filter have to filter these out.

atom/github,atom/github,atom/github