Enabling tending of cache when status is Upkeep Required

[Klensor]

Fix for this issue: https://github.com/Thricehappy/EveScoutRescue/issues/211

Not entirely sure I've understood the problem correctly, but it does seem that it might be desirable for someone to tend a cache (and so reset the timer) even if they don't have the correct supplies to restock it.

[bikerunner]

Not sure if this PR is necessary. Seems to work for me without the change:

• create a cache in J100001 (I/II, 44444km, default pwd)
• set cache to "upkeep required"
• "Tend" button is enabled now
• tending as 'Healthy' and 'Expired' work
• setting the cache to 'Upkeep required' throw a message 'Could not set cache to 'Upkeep Required' as that is already its current status.'

I understand the issue as:

• the cache is set to 'Upkeep required' some time ago
• another pilot enters the system and opens the cache to refresh
• cache needs supplies but pilot does not have the supplies
• so it's possible to set the cache as expired (but cache stays in system for another 30 days)
• or the pilot sets 'Upkeep required' once more so the cache is registered as existing but need supplies

Issue requires to allow consecutive 'Upkeep required' actions and not the message that this is not possible.

@Thricehappy can you recheck this interpretation. @Klensor This PR may need a rework to match the issue.

[bikerunner]

This PR looks valid after one more review with time. It's possible to keep the cache alive without having supplies. This works well with the changed payout strategy.

[Thricehappy]

Change pushed to production.