feat(image_to_vm): Make disk layout configurable by VM type.

Use the smaller base format for 'raw' disk images since these will
usually be dd'd to a block device to create AMIs and what not. For
images using qcow2 and vmdk stick with the larger vm size.
fix(image_to_vm): Increase STATE in vagrant images to 16GB

Vagrant users are accustomed to much larger disk sizes so lets give it
to them. I'm leaving the others as-is since it is easier to grow than
shrink disks if anyone has a particular size they need.
fix(build_library): Drop default 'base' layout to 512MB for STATE.

This will further reduce the amount of dd'ing required when using block
devices.
Merge pull request #98 from marineam/image-size

Image size