Istio 1.2.8 and 1.1.17 now available

[oaktowner]

Hi Team,

We are pleased to announce the availability of Istio 1.2.8 & 1.1.17. Please check out the following release pages for details:

https://istio.io/news/2019/announcing-1.2.8/
https://istio.io/news/2019/announcing-1.1.17/