Created new knife/tmux function

New function allows signing into multiple nodes with one command, provided they
match on either partial name, role, or tag.
Merge branch 'master' of github.com:zanshin/dotfiles

* 'master' of github.com:zanshin/dotfiles:
  added Gundo plugin, removed command-t stuff
  removed unused code from vimrc
  cleaned up vim plugins in vimrc
  changed vim <leader> to spacebar