builder/virtualbox: treat guest_additions_path as a template
builder/virtualbox: treat guest_additions_path as a template

TranscendComputing/packer,msabramo/packer,msabramo/packer,TranscendComputing/packer,suma/packer,smerrill/packer,smerrill/packer,patricklucas/packer,smerrill/packer,Kaixiang/packer,smerrill/packer,msabramo/packer,patricklucas/packer,msabramo/packer,Kaixiang/packer,suma/packer,zyegfryed/packer,zyegfryed/packer,patricklucas/packer,suma/packer,zyegfryed/packer,zyegfryed/packer,TranscendComputing/packer,Kaixiang/packer,TranscendComputing/packer,Kaixiang/packer,suma/packer,patricklucas/packer