* Add version label to the cluster.
According to the STUPS team the daemon that exports logs to scalyr
stops the export if the version label is missing.
* Move label names to constants.
* Run go fmt
- Set WAL_S3_BUCKET to point WAL-E where to fetch/store WAL files
- Set annotations/iam.amazonaws.com/role to set the role to access AWS"
The new env vairables are PGOP_WAL_S3_BUCKET and PGOP_KUBE_IAM_ROLE.
* 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
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;