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/js/blitz.go

@@ -1,14 +1,14 @@
 package js
 
 import (
-	"github.com/versenilvis/iris/commands/core"
+	"github.com/versenilvis/iris/spec"
 )
 
 func init() {
-	core.Register(&core.Spec{
+	spec.Register(&spec.Spec{
 		Name:        "blitz",
 		Description: "Show help for command",
-		Subcommands: []core.Subcommand{
+		Subcommands: []spec.Subcommand{
 			{Name: "build", Description: "Creates a production build"},
 			{Name: "codegen", Description: "Generates Routes Manifest"},
 			{Name: "console", Description: "Run the Blitz console REPL"},
@@ -28,7 +28,7 @@ func init() {
 			{Name: "autocomplete", Description: "Display autocomplete installation instructions"},
 			{Name: "shell", Description: "Shell type"},
 		},
-		Options: []core.Option{
+		Options: []spec.Option{
 			{Name: "--help", Description: "Show help for command"},
 			{Name: "-p", Description: "Set port number"},
 			{Name: "-H", Description: "Set server hostname"},