Previously, the controller fetched the Oauth token once at start, so eventually the token would expire and the operator could not create new users. This commit makes the operator fetch the token before each call to the Teams API.
* move statefulset creation from cluster spec to the separate function
* sync cluster state with desired state;
* move out from arrays for cluster resources;
* recreate pods instead of deleting them in case of statefulset change
* check for master while creating cluster/updating pods
* simplify retryutil
* list pvc while listing resources
* name kubernetes resources with capital letter
* do rolling update in case of env variables change
DNS name is generated from the team name and cluster name.
Use "zalando.org/dnsname" service annotation that makes 'mate' service assign a CNAME to the load balancer name.
introduce Pod events channel;
add parsing of the MaintenanceWindows section;
skip deleting Etcd key on cluster delete;
use external etcd host;
watch for tpr/pods in the namespace of the operator pod only;