K8s list deployments (#921)

* Outline of ListDeployments method

* Added implementation of DeploymentList

runtime/kubernetes/client/kubernetes.go

@@ -4,9 +4,30 @@ package client
 type Kubernetes interface {
 	// UpdateDeployment patches deployment annotations with new metadata
 	UpdateDeployment(string, interface{}) error
+	// ListDeployments lists all micro deployments
+	ListDeployments(labels map[string]string) (*DeploymentList, error)
 }
 
 // Metadata defines api request metadata
 type Metadata struct {
+	Name        string            `json:"name,omitempty"`
+	Labels      map[string]string `json:"labels,omitempty"`
 	Annotations map[string]string `json:"annotations,omitempty"`
 }
+
+// DeploymentList
+type DeploymentList struct {
+	Items []Deployment `json:"items"`
+}
+
+// Deployment is Kubernetes deployment
+type Deployment struct {
+	Metadata *Metadata `json:"metadata"`
+	Status   *Status   `json:"status"`
+}
+
+// Status is Kubernetes deployment status
+type Status struct {
+	Replicas          int `json:"replicas"`
+	AvailableReplicas int `json:"availablereplicas"`
+}