modify upgrade/rollback tests/roles to actually verify that they were successful

[miabbott]

Embarrassingly, we have no explicit check that when a user does rpm-ostree upgrade or rpm-ostree rollback, that the action was successful.

We should make changes to verify things like:

• booted commit has changed
• boot loader config has been updated
• rpm-ostree status reflects change

cc: @dustymabe

[dustymabe]

@miabbott thanks for opening this - i had it on my todo list, but then got busy :)

[mike-nguyen]

#164 should add some coverage to validate upgrades, rollbacks, and deploys but we probably want to add the validation to the improved sanity test.

[miabbott]

(3) Enhance the [a-h-t] 'sanity' suite to verify that upgrade/rollbacks were successful