Add a script for creating a VirtualBox image.
Add a script for creating a VirtualBox image.

Issue 1027 (http://code.google.com/p/chromium-os/issues/detail?id=1027)

Review URL: http://codereview.chromium.org/502014

nicescale/scripts,nicescale/scripts,endocode/scripts,trnubo/scripts,marineam/coreos-scripts,smilart/scripts,sigma/coreos-scripts,marineam/coreos-scripts,glevand/coreos--scripts,endocode/scripts,BugRoger/scripts,mischief/scripts,mischief/scripts,gtank/scripts,smilart/scripts,andrejro/coreos--scripts,sigma/coreos-scripts,vmware/coreos-scripts,fivethreeo/scripts,fivethreeo/scripts,coreos/scripts,zhang0137/scripts,zhang0137/scripts,smilart/scripts,endocode/scripts,gtank/scripts,BugRoger/scripts,bcwaldon/coreos-scripts,nicescale/scripts,crawford/scripts,mjg59/scripts,crawford/scripts,sigma/coreos-scripts,mjg59/scripts,glevand/coreos--scripts,bcwaldon/coreos-scripts,mjg59/scripts,coreos/scripts,zhang0137/scripts,trnubo/scripts,andrejro/coreos--scripts,vmware/coreos-scripts,BugRoger/scripts,andrejro/coreos--scripts,bcwaldon/coreos-scripts,mischief/scripts,crawford/scripts,marineam/coreos-scripts,fivethreeo/scripts,vmware/coreos-scripts,trnubo/scripts,gtank/scripts