Add validation for time configuration changes in subsequent runs of Guardian

[mdedetrich]

What is currently missing?

Since its possible for users of Guardian to change certain configuration settings (ie. changing the TimeConfiguration from DAYS to MINUTES) we should add logic to detect these changes and act appropriately.

Additionally we should also introduce a check for detecting any currently existing uploads to make sure we don't accidentally lose any backups Furthermore we should also prevent concurrent backups to the same storage location (for obvious reasons).

How could this be improved?

Some brainstorming still needs to be done on what is considered appropriate. For example if someone changes the time configuration from MINUTES to DAYS what should we do here? i.e. should we immediately close the currently open MINUTE timeslot and then create a new object/file for the DAY slot?

Is this a feature you would work on yourself?

• I plan to open a pull request for this feature