Vagrant router integration and updated readme

This PR addresses https://trello.com/c/cQf9jDeE/555-3-provide-readme-and-vagrant-setup-for-routing.

Features:

1. readme detailing full router setup
2. integration with vagrant single machine environment
3. integration with vagrant clustered machine environment where the router is placed on a new, unregistered minion
I'm not sure this belongs in the Vagrant provision.  It would be better if this fit into the general cluster startup flow - it's not truly dependent on cluster start, and also means anyone starting a new VM is going to immediately start pulling a fairly large images.  As such, it's probably better to just have a simple script to install the router.  Most of the complexity here (finding the master IP) will go away as soon as we add a dynamic service for the master, which means this is really only temporary.