Checkpoint EdgeDevConfig with AuthContainer

[eriknordmark]

First commit Refactors the verification of AuthContainer to prepare for the second commit which is validating the authcontainer when reading the checkpoint.

PR also contains to unrelated changes: 3. The introduction of a check for having pushed edge node certs to the controller means that the device will not use /persist/checkpoint/config until it can reach the controller. Fixed to only apply defer on first boot. 4. Removed the sample dummy wpa_supplicant code since the existence of what looks like hard-coded passwords caused confusion.