feat(coreos_startup): generate host ssh keys
feat(coreos_startup): generate host ssh keys

if the stateful partition doesn't have ssh keys then generate them. We
don't need any fancy dependencies here for the sshd service because we
use socket activation for sshd.

zhang0137/init,BugRoger/init,zhang0137/init,crawford/init,coreos/init,endocode/init,marineam/coreos-init,coreos/init,coreos/init,crawford/init,BugRoger/init,nicescale/init,nicescale/init,endocode/init