Adding vim-commentary.
Adding some new undo/backup/swap features.

* Centralizing backups, swapfiles, and undo files.
* Turning on persistent undo.
* Ignoring undo files.
* Moving function keys down the keyboard some, F11 and F12 werent
  working on my laptop (MBP Retina).
Making sure no backup files are saved outside ...

of the central directory.