Add option to support paravirtual or hvm virtualization
version 3.0.0
fix readme
Revert "fix readme"

This reverts commit 701d09097989d8d2decbe6b78236d74a5e3f2c28.
Fix README
Better device naming
Update documentation
Use HTTPS instead of HTTP to fetch Canonical images.
Demonstrate checking GPG signature while downloading software in the example.