WIP: Ship Gopkg.toml via Godeps.json conversion

[sttts]

This adds conversion of Godeps/Godeps.json into Gopkg.toml. It constraints the k8s.io peer dirs by branch in case of normal branch commits, and to tags in case of kubernetes-x.y.z tags.

Here is a test project: https://github.com/sttts/kube-vendor-test.

Current status: dep ensure is failing:

• in the release-1.8 branch: https://gist.github.com/sttts/11ab31d30639dac60ce1e384588c15f0
• in the kubernetes-v1.9.4 branch (corresponding to the kubernetes-1.9.4 tag): https://gist.github.com/sttts/c41318d5fc580d63b22b93b8dc9d8a63

[fejta-bot]

Issues go stale after 90d of inactivity.
Mark the issue as fresh with /remove-lifecycle stale.
Stale issues rot after an additional 30d of inactivity and eventually close.

If this issue is safe to close now please do so with /close.

Send feedback to sig-testing, kubernetes/test-infra and/or fejta.
/lifecycle stale

[fejta-bot]

Stale issues rot after 30d of inactivity.
Mark the issue as fresh with /remove-lifecycle rotten.
Rotten issues close after an additional 30d of inactivity.

If this issue is safe to close now please do so with /close.

Send feedback to sig-testing, kubernetes/test-infra and/or fejta.
/lifecycle rotten
/remove-lifecycle stale

[fejta-bot]

Rotten issues close after 30d of inactivity.
Reopen the issue with /reopen.
Mark the issue as fresh with /remove-lifecycle rotten.

Send feedback to sig-testing, kubernetes/test-infra and/or fejta.
/close