Add cros_factory_install kernel command-line argument when running the factory install shim.
Add cros_factory_install kernel command-line argument when running
the factory install shim.

BUG=chrome-os-partner:6535
TEST=Ran factory install shim on Alex and in VM

Change-Id: I32761736d8565d16323c6962058b478511a3ee8c
Reviewed-on: http://gerrit.chromium.org/gerrit/10398
Reviewed-by: Hung-Te Lin <8a7fce4940baad93a69f5073b383c85deed9d9c4@chromium.org>
Reviewed-by: David James <f231dc574bbeb62604660cbc162d1b8642a0a3af@chromium.org>
Reviewed-by: Richard Barnette <9e7d66387742bf40b0d2548ef2b93e7c522ca0eb@chromium.org>
Tested-by: Jon Salz <02f606d7fe027b93db0ccb8283f0d43a8932fe7a@chromium.org>
Commit-Ready: Jon Salz <02f606d7fe027b93db0ccb8283f0d43a8932fe7a@chromium.org>

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