Currently it's a bit of an ordeal trying to get the atomic puush
required for AppVeyor to register a commit on the release branch
and also a tag. Looks like AppVeyor expects you to do release from
the master branch.

Inspired by @nschonni work in #1518 in an attempt to work around
this issue this PR instructs AppVeyor to ignore tags on non-release
branches.

Fingers crossed this makes like easier.

Closes #1518