StackSet shouldn't become ready if it's broken about stackset-controller

[dryewo]

It once accepted a stackset manifest that contained the following under spec.stackTemplate.spec:

service:
  ports:
  - name: ingress
    port: "80"
    protocol: TCP
    targetPort: "8080"

Port numbers are strings, which is not valid. It successfully created a couple of stacks then.

Later, new stacksets (other, not this one) were not processed, no new stacks were created (#48).

Ideally, such validation errors should be detected very early and definitely not affect other stacksets.

[mikkeloscar]

Depends on #10 which depends on Kubernetes v1.11

[mikkeloscar]

Fixed in #52