CHANGELOG: update Go, etcd and k8s to latest
### Changed
+- Update Go version to 1.11.2
+- Update etcd to v3.3.10
+- Update k8s to 1.11.4
+- k8s codegen updates are longer performed via container. Go dependencies are now vendored
+ and updates are performed with shell script locally.
+
### Removed
### Fixed
+
- Fixed leaking http connections while verifying backup snapshots. [#1976](https://github.com/coreos/etcd-operator/pull/1976)
### Deprecated
