feat: add support for Kubernetes 1.10.13 (Azure#497)

See https://github.com/kubernetes/kubernetes/releases/tag/v1.10.13

feat: update VHD image to 2019.02.12

Includes Moby 3.0.4.

fix: containerd downloads every time (Azure#458)

chore: update git-chglog configuration for releases (Azure#314)

fix: revert PodDisruptionBudget definitions (Azure#300)

use 2018.12.19 image (Azure#186)

use latest VHD image (Azure#180)

Quick documentation rationalization (Azure#152)