a few cleanups

[gammons]

Hi Andrew,

I have made a few cleanups to your Uncle Bob - style rails app, namely getting rid of the pg gem in favor of sqlite3, and just a couple things I saw when studying the code.

Overall I like this approach. My thoughts on this subject is that most of the primary directories (boundaries, interactors, entities), could be encapsulated into a gem, which rails/sinatra/whatever could then require.

It's nice to see other ruby/rails developers starting to flesh out this approach to system architecture. My company will be using an architecture like this for the next revision of our product.