vivid server release 20151219 i386 server/releases/vivid/release-20151219/ubuntu-15.04-server-cloudimg-i386.tar.gz ubuntu-vivid-15.04-i386-server-20151219 vivid server release 20151219 amd64 server/releases/vivid/release-20151219/ubuntu-15.04-server-cloudimg-amd64.tar.gz ubuntu-vivid-15.04-amd64-server-20151219