A rake task to automatically do the first time setup

[phansch]

Not sure if that's possible or not.
After running bundle install, I'd love to just call rake setup to install dependencies, setup the postgres user and create the .env files locally. This would also have to take in account different operating systems.

In order to test this somewhat nicely, we should extract this into it's own module and just call the methods from the rake task.

rel #7