builder/googlecompute: added support for all standard VM images

Also fixed the error message to be clear that the image was not found in any of
the projects that we attempted to search, rather than keep the error message
from the last project, which may be confusing to users.
Added CoreOS, OpenSUSE, and Windows projects for searching images.
Merge pull request #1350 from mbrukman/googlecompute-driver-vm-images

builder/googlecompute: added support for all standard VM images