Adds ackrc (configures ack-grep)
Cleanup vimrc

Update some comments, remove some old commands
Adds sudo.vim plugin

sudo.vim allows me to edit files as root without requiring root for the
whole session. This means that there is less code running as root, and I
can keep my user-level configuration when editing files as root.
Adds MarcWeber/vim-addon-local-vimrc

I was using `set exrc` for loading project-level vimrc files, but it
doesn't traverse up the directory tree. Instead it only looks in the
current working directory. This will the traverse the whole tree.

I'm also asked before a vimrc file is sourced (to be safe), and the
results of my approval/denial is stored via the file hash.