refactor(commands): separate commands and its core into two folders (#32)

- I think it would be better if one for commands only, one for the spec
handling core logic so people won't be confused by the core logic inside
the commands folder (cleaner I guess)
- Regen docs

commands/sys/rancher.go

@@ -1,14 +1,14 @@
 package sys
 
 import (
-	"github.com/versenilvis/iris/commands/core"
+	"github.com/versenilvis/iris/spec"
 )
 
 func init() {
-	core.Register(&core.Spec{
+	spec.Register(&spec.Spec{
 		Name:        "rancher",
 		Description: "Output format:",
-		Subcommands: []core.Subcommand{
+		Subcommands: []spec.Subcommand{
 			{Name: "ls", Description: "List all apps in the current Rancher server"},
 			{Name: "delete", Description: "Delete an app"},
 			{Name: "APP_NAME/APP_ID", Description: "The name of the app to delete"},
@@ -56,7 +56,7 @@ func init() {
 			{Name: "token", Description: "Authenticate and generate new kubeconfig token"},
 			{Name: "help", Description: "Shows a list of commands or help for one command"},
 		},
-		Options: []core.Option{
+		Options: []spec.Option{
 			{Name: "--format", Description: "Output format: 'json', 'yaml' or custom format"},
 			{Name: "--quiet", Description: "Only display IDs or suppress help text"},
 			{Name: "--help", Description: "Show help"},