brute-force replacement for `dpkg_autostart`:

* the `dpkg_autostart` cookbook was causing
  various issues with chef 11 that were affecting
  this and other cookbooks. this achieves a
  similar goal, but in a way that does not
  necessarily play well with other cookbooks that
  may rely on this functionality.
use lwrp vs. file to pin pgdg apt preferences
update current package list todo in README
cleanup formatting
use ruby 1.9 style hash syntax
Merge pull request #45 from phlipper/dpkg_autostart

remove dpkg_autostart