Subdomain exlcusions

Impliments #83

Tests included :+1: 

You might note that I used a hack to get around the domain middleware. This is only because the sample app uses all three middlewares, and as the rack stack bubbles up the domain middleware tries to change the database as well. I created the schema because I don't know how to work around this fact without removing that middleware. This is probably something I'm doing wrong due to my lack of understanding.

However it works, as expected :tm: