GPU enabled with systemd startup

packer AWS AMI ami-c17672d7 installs:

• nvidia-375
• from cuda-repo-ubuntu1604_8.0.61-1_amd64.deb cuda-8-0
• cudnn-8.0-linux-x64-v5.1
• for python3 virtualenv and virtualenvwrapper
• tensorflow-gpu version 0.12.1
• startup optimization for the P100 for Ubuntu 16.04