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/runner/hexo.go

@@ -1,14 +1,14 @@
 package runner
 
 import (
-	"github.com/versenilvis/iris/commands/core"
+	"github.com/versenilvis/iris/spec"
 )
 
 func init() {
-	core.Register(&core.Spec{
+	spec.Register(&spec.Spec{
 		Name:        "hexo",
 		Description: "Draft for",
-		Subcommands: []core.Subcommand{
+		Subcommands: []spec.Subcommand{
 			{Name: "config", Description: "Get or set configurations"},
 			{Name: "help", Description: "Displays a help for each command"},
 			{Name: "command", Description: "The command to display help for"},
@@ -35,7 +35,7 @@ func init() {
 			{Name: "list", Description: "List all routes"},
 			{Name: "version", Description: "Display version information"},
 		},
-		Options: []core.Option{
+		Options: []spec.Option{
 			{Name: "--no-clone", Description: "Copy files instead of cloning from GitHub"},
 			{Name: "--no-install", Description: "Skip npm install"},
 			{Name: "-p", Description: "Post path. Customize the path of the post"},