Replace 'vm: true' with 'env: flex' in yaml files.

[janlugt]

vm: true is deprecated.

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[janlugt]

I signed it!

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[theacodes]

Thanks, @janlugt - I think the endpoints one was using vm: true for a reason.

@sepehre @kdeus is there any reason the endpoints sample won't work on env: flex?

[janlugt]

I did the quickstart for endpoints this afternoon as part of a review, and gcloud did not accept the config until I changed vm:true to env:flex. I haven't tested the other two files, but I figure it would be the same. It's mentioned in the release notes here: https://cloud.google.com/appengine/docs/flexible/python/release-notes#november_15th_2016

[theacodes]

@janlugt good enough for me, thanks. @sepehre and @kdeus if you chime in with reservations post-merge let me know.

[kdeus]

Sounds fine. Looks like we just hadn't updated this sample to env: flex yet. Thanks!

[sepehre]

Yes, flex everywhere! Onwards! :D