AU update generator script: support for new style full updates
AU update generator script: support for new style full updates

A corresponding CL adds support for the delta generator to generate
new style full updates. This CL adds support for creating new style
full updates to the common update payload generator script.

This does not change the defaults, so generating a full update still uses
the old style.

BUG=7248
TEST=generated/applied full update on host

Review URL: http://codereview.chromium.org/3604011

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