Add vimtodo submodule

.gitmodules

 [submodule "dotfiles/vim/bundle/vim-markdown"]
 	path = dotfiles/vim/bundle/vim-markdown
 	url = https://github.com/plasticboy/vim-markdown.git
+[submodule "dotfiles/vim/bundle/vimtodo"]
+	path = dotfiles/vim/bundle/vimtodo
+	url = https://github.com/mivok/vimtodo.git

dotfiles/vim/bundle/vimtodo

+Subproject commit d977c98e5d6a7a5dfb75a7a4faed3e88865031bc