add groups support

Using groups simplifies the administration of multiple accounts by
letting you assign settings once to a group, instead of multiple
times to each individual user.

Signed-off-by: Nicola Murino <nicola.murino@gmail.com>

cmd/revertprovider.go

@@ -58,7 +58,6 @@ Please take a look at the usage below to customize the options.`,
 func init() {
 	addConfigFlags(revertProviderCmd)
 	revertProviderCmd.Flags().IntVar(&revertProviderTargetVersion, "to-version", 15, `15 means the version supported in v2.2.x`)
-	revertProviderCmd.MarkFlagRequired("to-version") //nolint:errcheck
 
 	rootCmd.AddCommand(revertProviderCmd)
 }