Add argument 'no' commit/status option -u|--untracked-files

This new argument teaches Git to not look for any untracked files,
saving cycles on slow file systems, or large repos.

Signed-off-by: Marius Storm-Olsen <marius@trolltech.com>

Documentation/git-commit.txt

@@ -157,6 +157,7 @@ The mode parameter is optional, and is used to specify
 the handling of untracked files. The possible options are:
 +
 --
+	- 'no'     - Show no untracked files
 	- 'normal' - Shows untracked files and directories
 	- 'all'    - Also shows individual files in untracked directories.
 --