Pipe dream: Builds -> bintray (free for OSS)

[jblaine]

It would be rad to have binaries built and pushed from Travis. JFrog's bintray.com binary distribution service is free for OSS projects.

The Travis integration is documented here, but the page is timing out for me right now: https://docs.travis-ci.com/user/deployment/bintray

[gorsuch]

Thanks @jblaine - I'll give it a look over this week!