havener release v0.18.0

Changes

Removed the helm packages from havener to solely rely on the helm CLI binary. Thanks for @qu1queee for the major refactoring and addition of integration tests.

Without the helm package blocking it anymore, the internal libraries to communicate with the Kubernetes master were bumped to client-go version v1.11 and Kubernetes cluster version 1.14. The libraries should work with older cluster versions, too.