have travis squash images before uploading them to docker hub
have travis squash images before uploading them to docker hub

nanobox-io/nanobox-docker-build,pagodabox/nanobox-docker-build,nanobox-io/nanobox-docker-build,nanobox-io/nanobox-docker-build,nanobox-io/nanobox-docker-build,pagodabox/nanobox-docker-build