Refresh timestamp and snapshot metadata if necessary

[doanac]

Not totally sure we must have this for this milestone but keeping it here as a place holder.

[doanac]

@vkhoroz - one reason we may wind up needing this (but not as milestone 2): If people use this to switch apps, they may be on a version they like and simply want to reconfigure a device. A little bit of an edge case and I think we can point in docs for how to resign an existing update. But something to think about

[vkhoroz]

@doanac IIUC the problem here (applicable to aktualizr-lite) is that once TUF metadata expires, TUF checks on local device metadata will fail, preventing the app switch, right?

@mike-sul is there the same limitation with fioup?
How hard would it be to allow the app switch if the TUF expiration check fails (for the local data only)?

[doanac]

We don't verify TUF in fioup, just parse it for available targets.

[mike-sul]

is there the same limitation with fioup?

@vkhoroz As Andy already stated the fioup does not support TUF at all.

[vkhoroz]

That means, with fioup an app switch does not need this feature at all.

[doanac]

Correct. This would be for paying customers on aklite

[doanac]

This issue will be fixed by PR #191