Engine: Enable Cloud-Init SSH login via public key

Fixes:
1. Root is able to login via public key and password
2. Root password is not expired, i.e. no need to change password first
login (only if password was set)

Change-Id: Idb48fe4306f803aca801c03ddf29f010eaeb635f
Bug-Url: https://bugzilla.redhat.com/1063518
Signed-off-by: Shahar Havivi <shaharh@redhat.com>