Also fixed get latest image logic in image_to_vm and allowed for using the most recent image in cros_run_vm_test to follow other shell convention of using latest.
Change-Id: I60ed4c03d609500da7f6ae34ef57ba2e32f4b0bb
BUG=
TEST=Tested by running image_to_vm with --full and cros_run_vm_test with suite_Smoke
Review URL: http://codereview.chromium.org/3597001