Initial k8s support in libplayground (#216)

* Initial k8s support in libplayground

* Make tasks never give up + custom event for k8s cluster status

scheduler/task/types.go

@@ -0,0 +1,13 @@
+package task
+
+type ClusterStatus struct {
+	IsManager bool   `json:"is_manager"`
+	IsWorker  bool   `json:"is_worker"`
+	Instance  string `json:"instance"`
+}
+
+type ClusterPorts struct {
+	Manager   string   `json:"manager"`
+	Instances []string `json:"instances"`
+	Ports     []int    `json:"ports"`
+}