Use go 1.11 for Dockerized Makefile targets
Use go 1.11 for Dockerized Makefile targets

Previously, we used the Go 1.9 image for our dockerized targets in the
Makefile. The k8s project mandates Go 1.11 for k8s 1.13+
(https://github.com/kubernetes/community/blob/master/contributors/devel/development.md),
so there's no reason not to use Go 1.11 here.

I've verified all existing dockerized targets still work with go 1.11.

bgrant0607/community,bgrant0607/community,pwittrock/community,kubernetes/community,pwittrock/community,kubernetes/community,kubernetes/community