Move environment variables into their own file
Remove some debug echos
Rewrote `create-links` script for more awesomeness

* Stopped replacing perfectly good symlinks that have previously been
  created
* Made the blacklist of files more explicit, fixed the README/Readme.md
  blacklist entry
* Made the script less verbose
* Used variables better, instead of always doing ``pwd`/$file` and
  `~/$file`
* Made the script work when invoked outside of the repo