Use single file for private git settings

.gitignore

 *~
 .*.swp
 .netrwhist
-*/gittum/private/*
+*/gittum/private.gitconfig
 */vim/bundle/private/*

dotfiles/gittum/bin/setup

 printf "    path = $tilde/.gittum/before.gitconfig\n" >> ~/.gitconfig
 printf "    path = $tilde/.gittum/host/$host.gitconfig\n" >> ~/.gitconfig
 printf "    path = $tilde/.gittum/user/$user.gitconfig\n" >> ~/.gitconfig
-printf "    path = $tilde/.gittum/private/gitconfig\n" >> ~/.gitconfig
+printf "    path = $tilde/.gittum/private.gitconfig\n" >> ~/.gitconfig
 printf "    path = $tilde/.gittum/after.gitconfig\n" >> ~/.gitconfig