We should just do `git clone --recursive` instead of doing an
extra provisioning step.

Fixes #297
props @zamoose
Supply -q (quiet mode) when wp script calls vagrant ssh

This prevents the noise from "Connection to 127.0.0.1 closed." being output with each WP-CLI command.
Merge branch 'wp-cli-ssh-quiet-mode' into develop
Defailt to SUBDOMAIN_INSTALL and let COOKIE_DOMAIN be HTTP_HOST