Enable subdomain multisite installations

Dropped dependency on `vagrant-hostsupdater` in favor of [`landrush`](https://github.com/phinze/landrush). `landrush` spins up a small dns server that allows us to use wildcard subdomains, a requirement for subdomain multisite installs. Let me know what you think!
This should still be `false` by default right? Not sure we want it `true`.