Allow client to pull inventory information without PXE booting

[astrugatch]

It would be helpful for the client to be able to pull and report inventory information on machines without needing them to reboot.

I am deploying the client to machines that are already out in the field to get them into my host list for later. Forcing a reboot is disruptive to the current users, and right now I can’t even use the PXE inventory task as they aren’t set for PXE to be their primary boot device. adding this feature to the client would be really helpful.

[Sebastian Roth]

Cross linking this: https://forums.fogproject.org/topic/12506/client-inventory-option