[play] Set up automated builds for the play package

[yuvipanda]

Ideally, it would make a new container image tagged with the git hash for every commit. This is currently not possible on Dockerhub (which only gives you a 'latest' tag).

Our options are:

1. Used tagged builds in DockerHub. This would make a new build of play every time there's a tag made like 'play-*'. This won't give us an image per commit though, and would require a new tag to be made every time we want to deploy. This seems like too much coupling...
2. Use travis-ci on this repo to build and push a docker image. This requires setting sudo: true in travis.yml, which is going to slow down your tests (there's no way to do that only for post-merge builds I can tell). Not sure if you want this
3. ???

[rgbkrk]

We could have another repo that does regular builds, possibly using Travis CI's Cron Jobs feature or even just triggering the other repo after we've shipped the latest version of @nteract/play.

[stale[bot]]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[stale[bot]]

This issue hasn't had any activity on it in the last 90 days. Unfortunately we don't get around to dealing with every issue that is opened. Instead of leaving issues open we're seeking to be transparent by closing issues that aren't being prioritized. If no other activity happens on this issue in one week, it will be closed. It's more than likely that just by me posting about this, the maintainers will take a closer look at these long forgotten issues to help evaluate what to do next. If you would like to see this issue get prioritized over others, there are multiple avenues 🗓:

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