Do some VM customization (VirtualBox only)

* Boot into GUI mode
* Change guest memory to 1024 MB

Signed-off-by: Gianpaolo Macario <gianpaolo_macario@mentor.com>
Explain how to login into the guest VM
Fix typo
Merge pull request #1 from gmacario/devel

Customize VirtualBox VM: Add GUI, 1024 MB memory