Reliably build Debian 8 Jessie via packer.io
o Support building Debian 8 Jessie box images using Packer.io.  We must
  (presently) patch the VMware 6.0.2 tools to build on Linux 3.12+.
o Packer.io builds VMware images identified as "vmware_desktop", while
  Vagrant wants "--provider vmware_fusion"; handle both in Vagrantfile.
o Use a snapshot of the Debian 8 nightly netinst iso, for consisentcy
o Mount the cpppo/vagrant/debian/../../.. host directory on $HOME/src
  via NFS, due to ... issues with HGFS on OS-X Mavericks.