I need more control over appveyor builds, please

[silkentrance]

@raszi

With #121 I need to have more control over the appveyor jobs as they are constantly hitting a timeout (1hr per build), with 5 builds per commit this is not acceptable 😁.

While I could be fixing things on my windows machine, I would rather have it to work in the CI environment.

Please see https://help.appveyor.com/discussions/problems/6493-user-permissions-button-to-cancel-build-not-visible for more information.

[silkentrance]

@raszi having to wait for appveyor builds to fail is a PITA, please give me some control over the build jobs, so that I can stop/restart them as needed.

The same goes for travis-ci builds. Here I also need to be able to stop/restart builds.

[raszi]

After a short struggle with AppVeyor I believe I succeeded. Could you please check whether you have the right permissions?

[silkentrance]

Thank you very much. Works like a charm 👍