re-enable database config, add postgres header to vagrant provisioning

I pulled the latest code and tried running the tests - they didn't work because of missing postgres headers. I remembered what we did last night and added it to the vagrant provisioning script. Running "vagrant provision" from the featsofdaring directory will install any missing stuff.

Also I had to uncomment the config/database.yml files so the tests would run. We'll want a CI server to make sure things are in order. I made [a chore](https://www.pivotaltracker.com/story/show/75050722) for that