Use postgres in development

This is an important update, as it will change your configuration a bit; it's easy to get setup though.

Steps:
1. `$ brew update && brew upgrade && brew doctor`
2. If everything is OK with the doctor: `brew install postgresql`
3. Decide on how you want to deal with booting postgres, I followed the Homebrew instructions at output and will just launch it at boot. Optionally, you can manually launch it, and to make that easier check out (Lunchy)[https://github.com/eddiezane/lunchy]
4. Finally, `ARCHFLAGS="-arch x86_64" gem install pg`