Enable downloadable wheel builds on Appveyor - #1815

Changes Unknown when pulling 873566a on techtonik:master into * on python-pillow:master*.

Changes Unknown when pulling a24581b on techtonik:master into * on python-pillow:master*.

Is there anything in the build script that has to change for this to work?

I think I'm going to merge this with a branch that's uploading to s3, so that they're hosted somewhere.

Build script needed change to run two commands instead of one. Artifacts are hosted on Appveyor, but could be uploaded anywhere.

So in light of #1818 being merged, this PR can either be closed, or at the very least reworked.

Why pushing to S3 is better than leaving nighties on Appveyor?

Don't close, I'm going to pick bits from this. #1818 does eggs, this does wheels, I think the wheels are probably better to use than the eggs.

s3 gives up a record, it doesn't kill the ones on appveyor.

Rebased.

Changes Unknown when pulling 1fe4901 on techtonik:master into * on python-pillow:master*.

Functionality included in #1927