Fix docker-compose usage from host
Fix docker-compose usage from host

This commit rounds out the support for using DOCKER_HOST port forwarding to
communicate with the docker daemon in the guest. It solves two issues

- In the guest, /Users is symlinked to /home so that docker-compose path
expansion for volumes (i.e. .:/home/app/webapp:rw) resolves properly
- Updates the NFS export to use ~/vagrant_projects on both host and
guest.

adamaig/dev-with-docker-on-ubuntu