support for re-resolvable upstream

[splitice]

Includes two different ways to resolve the issue.

I have tested the patch way in staging environment. The other simpler method that doesnt require a patch relies on timers to re-evaluate.

[RekGRpth]

This is certainly very cool! But the main goal of this module is compatibility with standard NGINX without patches.

[splitice]

Then take the version without the patch, or potentially if you are able find a better way to do it.

I couldnt see a way to do it without a repeating timer for checks or a hook for post resolve.

Or I guess list the resolve directive as incompatible.