Feature request: git commit -A

[Aidan Feldman <aidan.feldman@gmail.com>]

Hi all-
I work on the education team at GitHub and do a fair number of Git
workshops.  One thing that I've always found difficult to explain to
newbies is how the staging area works, and why it's useful.  As a
hand-wave to simplify things, I usually have them use

git add -A
git commit -m "..."

to not really have to worry about untracked vs. modified/removed files
aren't included with `git commit -a` or `git add .`.  I would like to
add a `-A` flag to the `commit` command, which effectively does a `git
add -A` before committing.

I was trying to submit a patch myself, but couldn't even manage to
find where the various flags are defined :-)  Does the feature sound
reasonable?  Mind pointing me in the right direction of where this
would be added?

Thanks!
-Aidan Feldman