Update submodules

M  .oh-my-zsh
M  .tmux/tmux-yank
M  .vim/bundle/vim-fugitive
M  .vim/bundle/vim-javascript

Automatically generated:
  source: .shell/funcs:update_submodules()
  time:   Wed Mar 21 11:04:55 GMT 2018
  host:   lex.kodo.org.uk