Make it possible to allow or disallow future stamps per instance

[cmkramer]

As far as I can tell from the instructions I'm limited to setting this globally by updating the value in the service. It would be really nice if I could set this on a per-stamp-basis.

Currently I have a case where at one location I want to allow stamps in the future, and at another I want to disallow, this can be on one page. If this is somehow possible, please do tell, but if not, it would be great if you could add an additional scope parameter that can be set to overrule this per instance.

[yaru22]

@cmkramer There is no way of doing it as of now. I welcome you or other people to create a pull request for this feature. I'll be happy to merge. Thanks.