Introduce a JSON output table mechanic

- Create JSONTable as a proxy/extension to tablewriter which can also output JSON.
- Implement machine readable output for `server list` and `recipe list`

cli/server/list.go

@@ -18,6 +18,7 @@ var serverListCommand = cli.Command{
 	Usage:   "List managed servers",
 	Flags: []cli.Flag{
 		internal.DebugFlag,
+		internal.MachineReadableFlag,
 	},
 	Before: internal.SubCommandBefore,
 	Action: func(c *cli.Context) error {
@@ -29,8 +30,11 @@ var serverListCommand = cli.Command{
 
 		tableColumns := []string{"name", "host", "user", "port"}
 		table := formatter.CreateTable(tableColumns)
-		defer table.Render()
-
+		if internal.MachineReadable {
+			defer table.JSONRender()
+		} else {
+			defer table.Render()
+		}
 		serverNames, err := config.ReadServerNames()
 		if err != nil {
 			logrus.Fatal(err)