Add configuration option for default untracked files mode

By default, the untracked files mode for commit/status is 'normal'

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

Documentation/config.txt

@@ -1013,6 +1013,25 @@ status.relativePaths::
 	relative to the repository root (this was the default for git
 	prior to v1.5.4).
 
+status.showUntrackedFiles::
+	By default, linkgit:git-status[1] and linkgit:git-commit[1] show
+	files which are not currently tracked by Git. Directories which
+	contain only untracked files, are shown with the directory name
+	only. Showing untracked files means that Git needs to lstat() all
+	all the files in the whole repository, which might be slow on some
+	systems. So, this variable controls how the commands displays
+	the untracked files. Possible values are:
++
+--
+	- 'no'     - Show no untracked files
+	- 'normal' - Shows untracked files and directories
+	- 'all'    - Shows also individual files in untracked directories.
+--
++
+If this variable is not specified, it defaults to 'normal'.
+This variable can be overridden with the -u|--untracked-files option
+of linkgit:git-status[1] and linkgit:git-commit[1].
+
 tar.umask::
 	This variable can be used to restrict the permission bits of
 	tar archive entries.  The default is 0002, which turns off the

Documentation/git-commit.txt

@@ -161,6 +161,10 @@ the handling of untracked files. The possible options are:
 	- 'normal' - Shows untracked files and directories
 	- 'all'    - Also shows individual files in untracked directories.
 --
++
+See linkgit:git-config[1] for configuration variable
+used to change the default for when the option is not
+specified.
 
 -v|--verbose::
 	Show unified diff between the HEAD commit and what