website: inherit font scheme
Added the Ubuntu image project for GCE.

The documentation:
https://cloud.google.com/compute/docs/operating-systems#ubuntu
shows that `ubuntu-os-cloud` is the proper project name.
Merge pull request #1676 from mbrukman/gce-ubuntu

Added the Ubuntu image project for GCE.
Merge remote-tracking branch 'upstream/master'
prepared for merging with core Packer