script: Update prerequisites in release-vm-images

Signed-off-by: Lewis Marshall <lewis@lmars.net>
script: Remove duplicate clean up in release-vm-images

Signed-off-by: Lewis Marshall <lewis@lmars.net>
util/packer: Give user access to tup fuse mounts

Signed-off-by: Lewis Marshall <lewis@lmars.net>
Merge pull request #381 from flynn/vm-fixes

VM image fixes