Create mountpoint for Vagrant synced folder

This small fix allows the image to be used from the Vagrant Docker provider

See http://docs.vagrantup.com/v2/docker/

As an example of use please see https://github.com/gmacario/vagrant-ubuntu1404

Signed-off-by: Gianpaolo Macario <gmacario@gmail.com>
Merge branch 'fix-issue-159'