MacOS was having isues with DHCP for NFS shared folder

Signed-off-by: Mark Charlebois <charlebm@gmail.com>

Virtualbox has issues with certain operations on shared folders
using the default sharing mechanism. These are overcome using
NFS sharing.

On Ubuntu, sudo apt-get install nfs-kernel-server

Signed-off-by: Mark Charlebois <charlebm@gmail.com>

The environment variable HEXAGON_TOOLS_ROOT must be set to the location
of the installed HexagonTools. This could be a global install at
/opt/HEXAGON_Tools/7.2.10/Tools or it could be a personal install
${HOME}/Qualcomm/HEXAGON_Tools/7.2.10/Tools.

The default install path used by the installer is exported in the Vagrantfile.

There is still an issue that the hexagon linker fails on mmap of the shared folder.
If the shared folder was mounted via NFS for Linux and MacOS the problem would be
resolved.

Signed-off-by: Mark Charlebois <charlebm@gmail.com>

- Added "zip" package needed for build
- Run shell proviosioner as non-privileged (ie. "vagrant") user