Deployment, Loading Legislator Data, and Initial Polarization Views

This pull request expanded a little beyond what I initially wanted to do. There are 3 main components:

1. Use vagrant and an ubuntu virtual machine for development. I was getting increasingly frustrated doing development locally due to some dependency issues and other things so I went ahead and set up an initial vagrantfile for this project. There is a shell provisioner (`bootstrap.sh`) that handles most dependencies, but there are a few things you need to inside the vm - these are documented in the Readme for now.

2. Load and process legislators and ideology. This was way more work than it needed to be, but there were some major data quality issues in terms of consistent IDs for legislators between some of the datasets we are using. This required some creative solutions, which still don't get us 100 percent coverage, but get us pretty darn close.

3. Initial view for polarization (`/polarization`) - this view returns a JSON array that gives our measure of polarization (distance between average ideology of Republicans and Democrats for a given chamber and Congress).

Next step is to load bills/productivity data - which I think will cover just about all of the data we need at that point.

Also - I dropped South from installed_apps - it was creating some issues with migrating foreign keys and such. It was easier to start from scratch than try and manage migrations, maybe because I'm not so familiar with South. If this is an issue, I can add it back in.