refactor!: migrate to urfave/cli v1

Better flexible flags handling.

cli/app/app.go

@@ -1,21 +1,21 @@
 package app
 
 import (
-	"github.com/urfave/cli/v2"
+	"github.com/urfave/cli"
 )
 
 // AppCommand defines the `abra app` command and ets subcommands
-var AppCommand = &cli.Command{
+var AppCommand = cli.Command{
 	Name:      "app",
-	Usage:     "Manage apps",
 	Aliases:   []string{"a"},
+	Usage:     "Manage apps",
 	ArgsUsage: "<app>",
 	Description: `
 This command provides all the functionality you need to manage the life cycle
 of your apps. From initial deployment, day-2 operations (e.g. backup/restore)
 to scaling apps up and spinning them down.
 `,
-	Subcommands: []*cli.Command{
+	Subcommands: []cli.Command{
 		appNewCommand,
 		appConfigCommand,
 		appRestartCommand,