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/ops/pod.go

@@ -1,17 +1,17 @@
 package ops
 
 import (
-	"github.com/versenilvis/iris/commands/core"
+	"github.com/versenilvis/iris/spec"
 )
 
 func init() {
-	core.Register(&core.Spec{
+	spec.Register(&spec.Spec{
 		Name:        "pod",
 		Description: "CocoaPods, the Cocoa library package manager",
-		Subcommands: []core.Subcommand{
+		Subcommands: []spec.Subcommand{
 			{Name: "name", Description: "The name of the podspec file within the Git Repository"},
 		},
-		Options: []core.Option{
+		Options: []spec.Option{
 			{Name: "--project-directory", Description: "The path to the root of the project directory"},
 			{Name: "--allow-root", Description: "Allows CocoaPods to run as root"},
 			{Name: "--all", Description: "Remove all the cached pods without asking"},