A few minor changes

This PR does a few things:

1. It upgrades middle man and dependencies to a more current version. This was the easiest fix for a problem I encountered with the project and my dev env. I figured it might be good to do anyway. I also removed 'Gemfile.lock' from .gitignore and checked it in to the repository as it should be included.
2. It comments out `@import "bootstrapValidator";` in _forms.css.scss. The referenced file didn't exist in the repo and was preventing CSS from compiling. Perhaps you just need to check that file into the repository? Probably a simple fix.
3. It adds a rack config file which allows pow to serve middleman projects (I use pow to run rack apps on my mac - http://pow.cx). If you're not using pow, this file won't hurt anything so I figured I'd commit it. Though, pow is awesome and I bet you'd like it. :+1: 

No obligation to accept this pull request. Though, I don't think it should hurt anything or make much of a noticeable difference. If you do merge it, be sure to `bundle install` before running the server (it'll whine at you).