Refactor store interfaces and provide database as example implementation

Refactor store interfaces and provide database as example implementation.

supersedes !237 (closed)

Relates to: #97 (closed)

cli/cmd/deviceList.go

@@ -46,11 +46,12 @@ var deviceListCmd = &cobra.Command{
 	Long:    "List all orchestrated network devices within the current PND.",
 
 	RunE: func(cmd *cobra.Command, args []string) error {
-		resp, err := pndAdapter.GetDevices()
+		respONDs, err := pndAdapter.GetDevices()
 		if err != nil {
 			return err
 		}
-		for i, dev := range resp {
+
+		for i, dev := range respONDs {
 			log.Infof("OND %v: name: %v, uuid: %v", i+1, dev.Name, dev.Id)
 			sid, err := uuid.Parse(dev.GetSbi().GetId())
 			if err != nil {