Add Kubernetes Auth Method

[hreeder]

Stackstorm-ha, by default, runs in Kubernetes (which is how I've got ST2 deployed). This PR should add support for Vault's Kubernetes auth method to the pack.

Draft, while I test it locally on my own deployment, but to give you the heads up this is coming.

[cognifloyd]

Oooh. This is pretty cool! Thanks!
config.schema.yaml will need to be updated to add role and auth_method=kubernetes.

[hreeder]

Oooh. This is pretty cool! Thanks!
config.schema.yaml will need to be updated to add role and auth_method=kubernetes.

Thanks for the catch, updated.

[hreeder]

@cognifloyd This should be good for review now. It's working in my environments suitably and we can access and retrieve vault secrets as necessary within our K8s environments.

I've also added a generic auth_mount_point config parameter as our setup makes use of custom mount points for different environments.

[cognifloyd]

#23 should fix the test errors here.

[cognifloyd]

#23 was just merged. Please merge in master. That should fix the tests.

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[nzlosh]

Closing as stale. Reopen with signed CLA and rebased master to have this PR merged.