include submodule dotfiles

`dotfiles` is my OS X dotfiles repo.
make .emacs a symlink of the OS X .emacs

.emacs is clearly cross platform (one side effect was that I decided
to install all the custom packages, some of which I won't need on
Ubuntu).
major overhaul of initial-setup.sh
system-update shortcut: add autoremove & autoclean
add completion to python interactive interpreter