add download script for headless install bundles for better CI automation
add download script for headless install bundles for better CI automation

joshwatson/binaryninja-api,joshwatson/binaryninja-api,Vector35/binaryninja-api,joshwatson/binaryninja-api,Vector35/binaryninja-api,Vector35/binaryninja-api,Vector35/binaryninja-api,Vector35/binaryninja-api,joshwatson/binaryninja-api,Vector35/binaryninja-api,joshwatson/binaryninja-api,Vector35/binaryninja-api