Implement Database Connection Code

[nfloersch]

All of the mock functions for various endpoints will eventually need to actually do CRUD stuff with a database.

So we need some code that will implement linking to the database from service/API.

We will probably use the pg library: https://github.com/brianc/node-postgres

However if whoever takes on this task wants to use a different NPM package / lib to connect, no problem, as long as it is current and supported with good documentation.

Details for the actual database are available from leadership... there is an existing Heroku PostGreSQL database waiting for this connection to happen.

I suggest starting with an existing working Mock function (/contacts) and implementing code that works into that, then abstracting back out from there.