fetch & clone: do not output progress when not on a tty

fetch & clone: do not output progress when not on a tty

This adds the option "--no-progress" to fetch-pack and upload-pack,
and makes fetch and clone pass this option when stdout is not a tty.

While at documenting that option, also document --strict and --timeout
options for upload-pack.

Signed-off-by: Johannes Schindelin <Johannes.Schindelin@gmx.de>
Signed-off-by: Junio C Hamano <junkio@cox.net>