[istio] Add chart

[osterman]

what

• Add istio helm release

why

• https://istio.io/docs/concepts/what-is-istio/#why-use-istio

references

• https://istio.io/docs/setup/kubernetes/helm-install/#option-2-install-with-helm-and-tiller-via-helm-install

[alebabai]

@osterman the same question for istio chart, is it okay to fork it to cloudposse charts-repository, because maintained version of the chart didn't have own helm-repository?

[osterman]

You can use this pattern to import it:
https://github.com/cloudposse/charts/pull/154/files#diff-0fa6756c0ad8c76b52d6de39a1eae178R2

[alebabai]

istio also required some changes in Kops template
https://istio.io/docs/setup/kubernetes/platform-setup/aws/

[alebabai]

Also if helm version is lower than 2.10.0 additional steps are required to install CRD.
https://preliminary.istio.io/docs/setup/kubernetes/helm-install.html