Cleans up image_to_live changes and handles errors more gracefully
Cleans up image_to_live changes and handles errors more gracefully

TEST=Tested by running image_to_live with correct formated images as well
as images that are missing either /var or dev_image directories.

Review URL: http://codereview.chromium.org/1705023

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