Quick workaround for accidentally clean of /home/vagrant while deploying

 stack.sh Now includes a cleanup for previous builds, and cleans
 instances path prior to install, this ends up cleaning /home/vagrant in
 the middle of the devstack install (using the module
 cookbooks/devstack) which point to /home/vagrant as default dir for
 instances directory.
Update URL for precise64.box - fixes #9

Fetched from Vagrant wiki

https://github.com/mitchellh/vagrant/wiki/Available-Vagrant-Boxes